Oh DKP - how I hate you. It's been a while, but S-a-S has finally had to implement a DKP system for Wrath raiding. We tried to avoid it as long as we could, but we're just getting too many issues with our /roll system.
Probably the biggest issue we've had with the /roll - and one we'll have anyway I'm sure - is our "Don't be a douche" rule. We kind of expect folks to know what's BIS for them, what's a real upgrade, and what would be better served in someone else's hands.
For example a retadin has an iLvl 213 and a DK has a 226 (BoH). A 232 drops - and the DK takes it. Douche move? Probably - but it's still an upgrade across the board. Same with say Pandora's Plea. BIS for a Paladin, decent trinket for any caster.
The problem with implementing a douche call is you get into Loot Council type modes. Who really should be determining which loot goes where? Even after the spirit nerf, it's still a big stat for trees and holy priests - yet warlocks gain spellpower from it as well. It's some tough calls.
So why I don't think DKP will solve this issue per-se, it will give folks the option of bidding big for an item they really want, and taking their chances with the RNG if it's an upgrade but not something they lust for.
Until WoWInsider, Blessing of Kings, and UnbearablyHOT covered this DKP system, I'd never heard of it. I like it a lot (in theory) - and am looking forward to using it in game - well, as much as you can look forward to any DKP system. It has built in controls for DKP bloat, allows raiders some measure of control for when they bid big, and seems fairly easy to implement.
I do wish we could run the loot on a pure /roll system, with no need to track who's won what, who should be passing, etc (like we do in our 10s), but there's always that one POS who rolls on everything, gets 20 pieces in one night, then disappears until the next content patch.