Just wanted to toss in a couple observations about hell level while they are still fresh on my mind. For the most part, the feel is about right, so these suggestions are more on the tweaking side.
Mob Difficulty: I love the way you have done mob traits in the game. I am also enjoying how hell level mobs can have 3 traits. The one draw back is that the mobs with traits are vastly more powerful than the regular mobs. This generally makes chain killing rather inefficient. What I normally found myself doing was pulling normal mobs one by one in order to complete quests. The chain bonus is nice, but it is really only efficient once you pull a few dozen or more. My suggestion would be to go one of two ways. One would be to give all mobs a chance to have 1-3 traits as they spawn in hell difficulty. This will keep the danger and still make them semi-doable in chains. The other would be to make chain pulls more beneficial (chances for better loot, higher xp in the hell levels, etc.)
Quest Bosses: The early hell level quest bosses are rather easy. In most cases, I found they were easier than regular mobs with traits. It would be good to give them a few buffs in order to keep them scary. On the flip side, there is a definite cutoff point of when this is true. I can't remember when, but after about half way, the boss fights go from extremely easy to extremely hard. It is roughly in the area when the boss fights begin spawning additional mobs with them. Sorry to be vague on this quest level, but I will try to keep a tab on it the next time through. At that point in the quest line, all quests become extremely difficult and you have a good chance of dying (exactly as it should be in Hell!).
Items: I am starting to see more of the elite items filter into the loot drops. I know this is an arduous task, so great job on the additions to date. I look forward to seeing the new items.
Level: I just hit level 96 with my ranger. I am not sure if it is intentional, but level 97 is about a 50% total XP increase. Taking into account the typical xp I am getting from mobs at this level, that will equate to about 1200-1400 kills. That being said, EQ had its own hell levels, so maybe this is part of the memories flooding back
I hope this helps, and yet again, great job on everything.