It's really amazing what you can work out when you have a good dialog with someone who disagrees with you. It requires that both parties are mature and a real exchange of ideas happens. Neither party may change their position, but both parties can come away with a better understanding of the overall situation. Often times some core issue is uncovered.
We were discussing the difficulty divide of 10s/25s and we both came to the conclusion that one of the core issues is Heroism/Bloodlust. 10s are currently balanced around the idea that your group may not have Heroism/Bloodlust while 25 mans are balanced around the idea that you do. That makes sense. In 10 mans you may not have a Shaman in your group, while it's fair to expect that out of 25 people, one of them will be a Shaman.
The consequence is that it makes Shaman very attractive to 10 man guilds and 10 man guilds that have Heroism/Bloodlust have an advantage at beating encounters. We love Heroism/Bloodlust in our group. One of the classes we'd love to add to our group for Cataclysm is an Elemental Shaman, and one of the main reasons is to give us a back up Heroism/Bloodlust if our Resto Shaman can't make it or wants to play his Mage.
10s could be tuned more closely to their 25 man counterparts if the Developers could assume Heroism/Bloodlust was available to all 10 man groups. There are several ways the Developers could do this such as adding in scrolls like the Scroll of Blessing of Kings or Scroll of Mark of the Wild that are being added in 3.3. But with Cataclysm on the horizon, I will put forth the not-at-all-new suggestion that Heroism needs to be given to another class.
But which class? This is a powerful buff and whichever class gets it will have an advantage in getting raid spots over other classes. So we need to be careful who we give it to.
I believe it has to be given to a hybrid. The 'pure' dps classes are brought for their pure untaxed dps, so by that logic they don't 'need' heroism. So let's eliminate Rogues, Hunters, Warlocks, and Mages from the mix.
I would love to build a case that Paladins should get Heroism, but Paladins already have a signature much desired buff in Blessing of Kings. You could make a fairly compelling argument that Kings is the best buff in the game, and that Paladins have more raid utility than just about any hybrid going. So, as much as it pains me, I have to eliminate my class, Paladins.
I think I'm also going to have to eliminate Druids. They have the signature buff of Mark of the Wild and Battle Rez and Innervate are also a very powerful utility.
The Buff from Paladins (Blessing of Kings) and Druids (Mark of the Wild) are so important that Blizzard is implementing a scroll in 3.3 so that groups without Paladins and Druids will have access to those buffs, mainly because they affect your Tanks buffed hit points. The other buff that comes under that umbrella is Power Word: Fortitude.
Priests are also powerful healers and maybe this is just my own perception but healers seem to be the hardest role to fill in end game raiding. They also bring the Spirit buff for casters and the various Shadow debuffs. Shadow Priests can fill the important replenishment role. So we are going to drop Priests out as a new Heorism class.
So what are we left with? Warriors and Death Knights.
Both of these classes are outstanding tanks and do competitive hybrid-taxed DPS. Both classes are limited to melee dps or tanking roles.
Warriors bring the HP buff Commanding Shout, the AP buff of Battle Shout, melee crit with Rampage and the Bleed debuff. Warriors bring the utility of increasing melee DPS with Sunder and Blood Frenzy. Mortal Strike is an important if situational ability.
Death Knights are valued for Horn of Winter, Abominations Might, Icy Talons, and Ebon Plaguebringer. Death Grip has some great utility, but is highly situational.
I'm the last guy you'd think would build a case for a major buff to either Warriors or Death Knights, but if you look at the situation, it does appear a case could be made that those two classes could use some additional utility when compared to the other hybrids. Giving Heroism to one or both classes would make it easier for the Developers to balance content as well as to give 10 mans greater access to this important buff.