After having read countless threats about how the raiding model in Wrath is broken, I find that I agree and disagree at the same time.
On the one hand, it is good that raids are accessible to everyone because everyone is able to enjoy the game. However on the other hand, the accessibility has lead to some lead to a dumbing down of some content and a general unbalancing in some areas.
First I'll start by saying, I play a lot of games, and I generally enjoy a challenge and play them on hard mode. If for example I play Call of Duty, I play directly on Veteran and I'm done with it. If the game only lets me play on normal mode and as a reward I have the veteran difficulty available after finishing it, well to hell with it, I won't play the same game twice because it won't give the same satisfaction.
What I don't like about the current raid model is that, the sense of accomplishment is gone for the more hardcore raiders, doing the boss in normal mode only to do it again in HM is never going to be the same as downing him for the first time in hard mode. There should be no need to do easy mode to progress in hard mode, the two difficulty settings should be separate, so progression is linear. Also a hard mode encounter should be more then just the same boss with more HP, damage and 1 extra twist or ability it should be something radical that changes the very way you kill him, like Sartharion 3D or Firefighter where.
So, what I suggest is this, when you found a guild, you have the choice of doing 10 man, 25 man or 25 man HM. However, once chosen you can't switch to another difficulty mode for at least 1 month. This would prevent guilds from clearing something on 1 mode and then switching to another just for badges.
All badge loot is balanced around only running one type of raid per week. If you chose to leave your old guild for whatever reason, perhaps you feel its time to go more hardcore, when you leave it you reset your path and can join any guild of 10, 25 or 25 HM, however you can only do this once per month, again to prevent abuse.
The difficulties of these modes will be aimed at the following.
10 man, will be the most casual setting, for people that don't have much time to commit but still want to see the game, this mode will feature the simplest fights and most forgiving, for example Sartharion without drakes, ToC 10 normal mode, or ICC 10 with 30% buff.
25 man, for people willing to put more time, and want a bigger challenge, this difficulty mode will feature fights somewhat like Ulduar 25 normal, ICC 25.
25 man HM is going to be for the cream of the crop and it will feature fights that are not only challenging but in some way richer then the other modes. Examples will be Sartharion 3D to what Sartharion alone was, Yogg 0 etc.
Advantages of the system.
1st Reduces boredom, part of the problem with all the difficulty modes is that, they are all available at once, and badge rewards tend to be so expensive that, it forces people to farm multiple difficulties which gets boring fast. With this system you'll only ever see the same raid 2 times and that is only if your guild disbands or you change guilds and that case will be rare. This way you can enjoy the dungeon more.
2nd Difficulty scaling will be way better. A major problem with the current model is, making progression from one tier of content to the other fun and challenging for all. Well, if all difficulty modes are open at the same time, that is quite impossible.
As an example, lets take the progression from ToC 25 to ICC 25. Gear level in ToC 25 was 245, gear level in ICC 25 is 264. However we also have 258 gear that could have been gotten by the really hardcore for completing ToGC 25.
Now if we balance fights to be challenging for people in ToC 25 gear then the people in ToGC 25 gear will find the fights too easy. If we balance for people in ToGC 25 gear, then the fights will be way too hard for people in ToC 25 gear.
However, if the only way to progress is either from ToC 25 normal to ICC 25 normal, then the jump will always be from 245 to 264, and that is easier to balance.
In the same way the jump from ToGC 25 to ICC 25 hard will always be from 258 gear setting to 277 and this is again easier to balance.
3rd The epic feeling or raiding will come back for the more hardcore, when you kill a boss it won't be with the thought of "but now I have to kill him on HM again", this time it will be for good and the sense of accomplishment will be there.
Also, because I know for sure I'm going to be asked how PuGs are going to be run, well its simple.
When the raid leader forms a raid he choses weather he wants it to be a 10, 25 or 25 HM raid. The raid leader can also be assisted in his quest to find new players with a new in game tool that can measure a players skill by stats such as, times killed a boss, successful raids participated in, number of times wiped, number of times left from a raid before its completion etc. The raid leader will also have a new option named "Finish raid", once pressed people get a 1 more point in their successfully raids completed tab, and can leave without repercussions, leaving before the raid leader does this, or before all bosses are killed means you get 1 quitter point. This can be sued to identify the good, loyal determined players from the bads, winers and quitters. This also lets a raid leader conclude a raid early if people can't kill all the bosses, as is the case in most ICC 25 pugs that can only kill the first 4 bosses.
Also, while in the PuG raid, everyone can give a vote to all the members of the raid, a "thumbs up" or "thumbs down". These votes can help indicate what players is good and what players is not. The raid leader can also be voted in a similar manner so you can check on the number of successful PuGs he has pulled of. Or if the leader is bad, or a ninja you can give him appropriate votes and this will be reflected and easy to see for everyone.
Once you kill 1 boss in any difficulty mode, be it 10, 25 or 25 hard, you are locked to that difficulty mode for the rest of the week.
Another idea would be to simply not allow non guilded players to run PuGs at all since it diminishes the value of a guild as a whole, but thats material for another topic.
This is my take on balancing the current raid model and also brining back the fun and challenge for hardcores while still keeping things fresh for everyone.