Ya I had to bail on hosting email, getting off of block lists and verifying that people even get your outbound email is near impossible at this point.

As i said i already have experience of hosting email, many different ways, etc

Will you use your selfhosted mail for important things? (Banking, official correspondence and so on)

I'm barely using email because have really few services that require an email (foss and selfhosting evangelism)

Can you promise a near 100% uptime? Otherwise, some email might not reach you.

I can promise you anything under these stars. And some of it would be true because my specialization is 0 downtime systems

How important is the Mail you send? Some (stupid) Blocklists generally block all IP ranges that are sold out by vps companies and other kinds of IAAS.

Never had any problems with the big hosters like do, linode, vultr, hetzner

If you register any accounts with your selfhosted mail, can you guarantee yourself that your email account is secure? Don't underestimate what an attacker can do with a compromised Mail account.

Selfhosting for many years, never got hacked because I take security seriously

Nowadays I pay a company to do the mail hosting

I'm trying not to pay companies when not necessary, and especially not for a "setup service"

Can you promise a near 100% uptime? Otherwise, some email might not reach you. Just lol. Mail get queued just fine by everyone. If you really concern , setup second MX.