To answer some of your questions:
It's a safe bet that your concerns are well founded. I am sure that 4-12 beers a day is affecting his health.
The doctor even seems to think the seizures and high blood pressure are related to his drinking.
There are a lot of us here who are considered "functional alcoholics." I've had my current job for 13 years, and I am able to pay all my bills even though I work part time. I'm a full time grad student, and I've been in a long term relationship with a wonderful partner.
The way I see it, you know what the problems are in your relationship. You talk of financial security and stability...what about emotional security and stability?
Have you expressed your sincere concern for your his health? How has he responded? Is he emotionally with you when he drinks, or does he seem to check out?
I think it all depends on 1) what you are expecting from this relationship, and 2) whether or not you are willing to accept him as is.