Currently to produce lab grown meat they still need a fair amount of biological material for input into the process. So while it does appear to be the lesser of the two evils, especially from an environmental perspective, it's not a purely ethical process. So I'm not sure how many vegetarians/vegans would be convinced to incorporate lab grown meat into their diet at this time.

Not the OP. I'm not a vegan, and not even a vegetarian - however, I have hugely cut down on meat consumption because our western diet expectation of having meat in every single meal is absurdly excessive, and in my case resulting in increased cholesterol and other health risks. So I've cut back massively on meat such that it's once a week, and something very lean.

Lab grown meat has all the problems that farmed meat has, by and large, in terms of health impacts and energy intensiveness.

The other thing is that since going to a mostly plant based diet, is I've found I simply do not miss meat, in particular I don't miss red meat at all. So even if lab grown red meat could be less unhealthy, I'll still give it a miss because plant based food is to be honest perfectly enjoyable. I would imagine many vegetarians and vegans won't eat lab grown meat because they just don't need it to enjoy food. I think it's such a shame that so many eat lots of meat "politically" that they won't even try reducing their meat consumption and finding other foods that are just as pleasurable, and a lot less damaging to their long term health.