I mentioned on the IRC (irc.quakenet.org:6667-6669, #chaosforge) that the beta badges I was going to skip would probably be the centurial ones because I find Ao100 tedious. This led to a bit of a discussion about how we could make Ao100 more of a unique and exciting experience. We came up with a few ideas...
Add in the special levels, but more spread out. Near the end (Level 70+ or so) you get Ao100-only special levels, which are incredibly challenging.
Add in Ao100-only special levels. My favourite was the mini-mortuary, a vile spin on classic arenas.
Make Ao100-only enemies. Someone suggested (possibly as a joke) AoD caves, where there's a whole bunch of demons/lost souls... and the AoD. You can shoot at him, of course, but that doesn't stop him from being twice as fast as a lost soul and having as much HP as the cyberdemon.
So what are your suggestions for it? Make them as excruciatingly difficult as you like, Ao100 is supposed to be the hardest challenge. Besides, you're dealing with level 16 marines with 5+ uniques here, they need a challenge.