In case you haven't heard, there's some really good news for 10-man raiding in Cataclysm. Maybe not so good for 25, but we'll see. The source is from the European forums found here. And to sum it all up, 10-man and 25-man raids will have the same loot drops in Cataclysm. There will also be only one raid lock-out for each. So, you don't have 25-man guilds also farming 10-man content and gearing up much faster than people that only run 10-man content.
To offset it, the 25-man content will drop more loot, and more gold as well. They still want 25-man content to be a more efficient way of gearing up. (Writer Warning: lots of math-type stuff ahead.)
So, let's play with this a bit. Let's say that trends continue, and each boss on 10-man raids drops 2 items (or 1 for every 5 players). An even way would be for 25-man bosses to drop 5 items (same 1:5 ratio). Making it slightly more profitable would mean 25-man would drop say 6 items. If loot tables are something like the first 3 bosses in ICC, there's 12 different items that will drop on 10-man. That means you have a 1 in 6 chance for your loot to drop in 10-man, but 1 in 2 chance for your loot to drop in 25-man.
But will you win it? I'll have to make some assumptions here. Let's assume gear is very homogenized. There will still be some differences though. For example, some hybrid classes will still have 2 sets of gear, especially those that require completely different stats (like a healing druid vs. a tanking druid). But for the sake of this conversation, let's say that we have a 10-man raid with one of each class. As a Shaman healer (best case), I get every single drop that's casting mail. (Only shaman in raid, and hunters don't want it.) As a cloth mage (worst case), I have to fight 2 other classes making my initial drop rate of 1 in 6 change to a loot rate chance to 1 in 18.
Our 25-man raid has to be guessed at. Let's assume 1 of each class/role. Where only 1 role for the class is available, we'll assume they bring two of those class (hunter, mage, rogue, warlock). We may have too many tanks (4), and probably not enough healers (4), but it's simply for illustration purposes. I also threw in another paladin healer (5 healers now) since they were in a armor group all by themselves. Here's what I came up with for this fictional raid:
|death knight dps|
|death knight tank|
So, your odds vary quite a bit here as well. You have anywhere from a 1 in 2 chance to get your item (paladin healer vs. paladin healer, or, shaman healer vs. shaman ranged, or, druid healer vs. druid ranged) all the way to a 1 in 6 chance (all clothies, or, all melee/tank plate wearers). So, the 1 in 2 chance that your item will drop becomes a 1 in 4 loot rate (best case scenario) or a 1 in 12 loot rate (worst case scenario), with a couple other odds in between.
Anyway... point being... I think this will be a great change. I'm still not sure it's completely on track. Like I've mentioned and has been said many times before, 10-man raiding can be more difficult than 25-man. If one person dies on 10-man, that's 10% of your raid. A 25-man death is only 4%. But if they made it completely equal, it would be the death to the 25-man raiding for sure. And while I have found that 10-man raiding is by far what I enjoy, there's still a special place in my heart for the 25-man stuff that I did all through TBC.