I've been using "Adjusted Average" since 3.0, myself. It gives Wizards a little of a bump, but, seriously, with 3hp a level, Wizards remain a good smack away from death anyway.
For me, as a GM, it just made my life easier. I knew the HPs of all the characters throughout their progression and it helped me balance encounters (since I like to run Adventure Path type things and then change them around, so I'm often plotting encounters out the PCs might not get to in a level or two).
It worked for my group.
I honestly don't like alot of randomization in character-generation aspects of the game. I'm also a strictly-pt-buy kind of guy. I mean, I played in a game about two years ago, the last I've played that we rolled for, and I rolled up a character with something like 17, 17, 16, 15, 14, 14 ... it helped that the GM was using 5d6, Reroll 1s, Drop Two Lowest. At that point, why not just let everybody play with all 16s and be done with it. In my time gaming in 2nd and early 3rd, it seemed like GMs kept messing with their "Rolling System" to give the players what they wanted ... which, honestly, was More-Better All 18s Guy.
I'm probably going to yoink that Negative Level rule. I've never been much of a fan for the system As Is. With AP games, like I run, if you let people Res or come in 1 level back, people usually opt to come in with a new character with more optimized equipment. I'd like to see people be willing to res up their PCs and stay attached to them.
Secretly, I don't like the flavor of Res, though. Not so much in that I don't like resurection IN GENERAL, but I don't like that the D&D universe seems to sort of ignore how easy it is for people to come back to life. Really it just divides the rich from the poor. But you still see murder mysteries and convoluted plotlines trying to avoid that res magic. "Oh, but he was poisoned with this super-special poison that won't let him be resed." Or the body is stolen or destroyed or whatever. Or the writer just forgets that a high level and wealthy NPC could be resed and the rest of the plotline is sort of null.
I like to use Action Points, instead. A character can be Left For Dead for a certain number of APs, regardless of HOW he died, and we write him in somehow. It works better for me than "Let's drag Bob's body back to town, here's his bag of diamonds." or "Oh no, our wizard died ... luckily we found this other wizard locked up here in the evil castle. Get in party formation, wizard we just met!"
--fje