Speaking as someone who was addicted to alcohol, I want to concur that functioning is simply a stage, and moderation is impossible for a true alcoholic.
From what you've described, he is one. I followed much the same pattern of gradually increasing intake, switching to vodka or vodka "add ons", still maintaining job and appearences while slowly eroding in the home around my spouse.
Plenty of red flags here and very little real action on his part. Talk is what alcoholics do to maintain status quo and protect their drinking. Even if he "means" it, past actions show you likely outcome.
If he really believes he can moderate (as I did many years) I do not think he will succeed. I haven't read a single account on this list of any real alcoholic who could. You don't relapse on heroin just a little, and drinkers can't seem to ever go back to just a glass or two. It's like being a little pregnant.
Wishing you the best., and hope is important, but remember it isn't a plan.
Back up and more support for you are critical right now.