I'm not the person you're replying to, but I think you missed the whole point of GarbageShoot asking you specifically about Allende.

just based on a small snippet of reading about them, I think in general [...]

I think this is the main problem here: a lack of knowledge about the historical context of "authoritarian" socialist projects, but nevertheless making generalized statements about them without even considering the material reasons why they were by necessity "authoritarian." Read up more about the history of Chile and consider what happened to Allende and the hope of a socialist Chile. Who came after Allende (and almost as important, who installed that successor)? Why do these events seem so familiar when learning about every other attempt, successful or not, to bring about a communist society? When you've done that, you will at the very least have a leg to stand on when criticizing so-called tankie authoritarianism.

I'd also suggest reading The Jakarta Method. Here's a somewhat relevant quote from it:

This was another very difficult question I had to ask my interview subjects, especially the leftists from Southeast Asia and Latin America. When we would get to discussing the old debates between peaceful and armed revolution; between hardline Marxism and democratic socialism, I would ask: “Who was right?”

In Guatemala, was it Árbenz or Che who had the right approach? Or in Indonesia, when Mao warned Aidit that the PKI should arm themselves, and they did not? In Chile, was it the young revolutionaries in the MIR who were right in those college debates, or the more disciplined, moderate Chilean Communist Party?

Most of the people I spoke with who were politically involved back then believed fervently in a nonviolent approach, in gradual, peaceful, democratic change. They often had no love for the systems set up by people like Mao. But they knew that their side had lost the debate, because so many of their friends were dead. They often admitted, without hesitation or pleasure, that the hardliners had been right. Aidit’s unarmed party didn’t survive. Allende’s democratic socialism was not allowed, regardless of the détente between the Soviets and Washington.

Looking at it this way, the major losers of the twentieth century were those who believed too sincerely in the existence of a liberal international order, those who trusted too much in democracy, or too much in what the United States said it supported, rather than what it really supported -- what the rich countries said, rather than what they did.

That group was annihilated.

Well, since you like reading (which is cool and good!) there's a neat book on Cybersyn, but I was actually going in a slightly different direction. I respect the project Allende lead, but it's undeniable that it was a catastrophic failure. Allende is one of many examples of attempting a gentle touch and underestimating the sheer brutality that is the reality of capitalist encirclement for a socialist state.

Allende was conciliatory when he should have been firm and his lax approach to purging (i.e. basically not doing it) is what very directly laid the groundwork for the coup that was the death of him and many other Chileans under one of the most vicious dictators the world has ever seen.

Someone recently reposted a Michael Parenti quote that I think discusses elements of this well:

You can look at any existing socialist country— if you don’t want to call them socialist, call them whatever you want. Post capitalist— whatever, I don’t care. Call them camels or window shades, it doesn’t matter as long as we know the countries we’re talking about. If you look at any one of those countries, you can evaluate them in several ways.

One is comparing them to what they had before, and that to me is what’s very compelling. That’s what so compelling about Cuba, for instance. When I was in Cuba I was up in the Escambia, which is like the Appalachia of Cuba, very rugged mountains with people who are poor, or they were. And I said to this campesino, I said, “Do you like Fidel?” and he said “Si si, with all my soul.” I remember this gesture, with all our souls. I said “Why?” and he pointed to this clinic right up on the hill which we had visited. He said, “Look at that.” He said “Before the revolution, we never saw a doctor. If someone was seriously ill, it would take twenty people to carry that person, it’d go day and night. It would take two days to get to the hospital. First because it was far away and second because you couldn’t go straight, you couldn’t cross the latifundia lands, the boss would kill you. So, you had to go like this, and often when we got to the hospital, the person might be dead by the time we got there. Now we have this clinic up here with a full-time doctor. And today in Cuba when you become a doctor you got to spend two years out in the country, that’s your dedication to the people. And a dentist that comes one day a week. And for serious things, we’re not more than 20 minutes away from a larger hospital. That’s in the Escambia. So that’s freedom. We’re freer today, we have more life.”

And I talked to a guy in Havana who says to me “All I used to see here in Havana, you call this drab and dull, we see it as a cleaner city. It’s true, the paint is peeling off the walls, but you don’t see kids begging in the streets anymore and you don’t see prostitutes.” Prostitution used to be one of the biggest industries. And today this man is going to night school. He said “I could read! I can read, do you know what it means to be able to read? Do you know what it means to be able not to read?”

I remember when I gave my book to my father. I dedicated a book of mine to him, “Power and the Powerless” to my father, I said “To my father with my love,” I gave him a copy of the book, he opened it up and looked at it. He had only gone to the seventh grade, he was the son of an immigrant, a working-class Italian. He opens the book and he starts looking through it, and he gets misty-eyed, very misty-eyed. And I thought it was because he was so touched that his son had dedicated a book to him. That wasn’t the reason. He looks up to me and he says ‘I can’t read this, kid” I said “That’s okay dad, neither can the students, don’t worry about that. I mean I wrote it for you, it’s your book and you don’t have to read it. It’s a very complicated book, an academic book. He says, “I can’t read this book.” And the defeat. The defeat that man felt. That’s what illiteracy is about, that’s what the joy of literacy programs is. That’s why you have people in Nicaragua walking proud now for the first time. They were treated like animals before, they weren’t allowed to read, they weren’t taught to read.

So, you compare a country from what it came from, with all it’s imperfections. And those who demand instant perfection the day after the revolution, they go up and say “Are there civil liberties for the fascists? Are they gonna be allowed their newspapers and their radio programs, are they gonna be able to keep all their farms? The passion that some of our liberals feel, the day after the revolution, the passion and concern they feel for the fascists, the civil rights and civil liberties of those fascists who are dumping and destroying and murdering people before. Now the revolution has gotta be perfect, it’s gotta be flawless. Well that isn’t my criteria, my criteria is what happens to those people who couldn’t read? What happens to those babies that couldn’t eat, that died of hunger? And that’s why I support revolution. The revolution that feeds the children gets my support. Not blindly, not unqualified. And the Reaganite government that tries to stop that kind of process, that tries to keep those people in poverty and illiteracy and hunger, that gets my undiluted animosity and opposition.

Here I mean to most emphasize the last paragraph, though the preceding paragraphs are certainly relevant. "Are there civil liberties for the fascists?"