About 10 versus 25 raid size split in Wrath, I made an assumption and drew a conclusion that the rewards would be demonstrably better in 25-man content as a consequence the difficulty level would be higher. Either that or the difficulty level would be exactly the same, the only reason for a reward difference being the Organization Boss that all larger guilds have to face every week.
However, I encountered with two "normal difficulty" raids: Sartharion with two drakes and Malygos. Without a stacked raid, our group–which took out Sartharion 25 with 2 drakes after only an hour and a half of tries–just, could not make any headway in the 10-man version. We had to settle for just one drake, and since we picked the baby dragon-spawner by accident that was no cake walk either. How about the rewards? Nothing anyone wanted, since we had been doing so much Sartharion 25 and Naxx 25. We were pretty psyched to get the achievement, though.
As for Malygos, we took him down with two healers. Tank healing was tight and raid healing was even dodgier. In the meantime, my mana pool dipped to scary levels. In my panic I hadn't been checking Mal's health bar. Malygos is a fight I love on 25s, but I have to say that the 10-man was breathtaking. It's exactly the kind of challenge I want that I know I can meet, or that gives me a chance to make improvements between attempts. It has me tempted to go back again. However, once again the rewards aren't in proportion to the difficulty. I'd say the loot is about on par with Kel'Thuzad's from Naxx 25–pretty darn good, but not nearly as nice as the stuff that comes out of the easier 25-person version of the same instance.
   Knowing what I know now, there's no reason to separate Emblem loot by normal/heroic raid tier. I think I definitely earned an Emblem of Valor or two for that Malygos kill. I had heard before that Sartharion with 3 drakes was absolutely monstrous on 10s, and I thought that was just a freak thing. But on the base of my own personal experience, I'll have to think that the phenomenon is more widespread. Either nothing in Naxx version is all that difficult for my guild but I remember that Kel'Thuzad is harder on both healers and melee-heavy groups in the smaller size. Like it or not, I draw the conclusion that raids who run 10-person content deserve the same compensation as 25-person raiders.
   The game needs to lure us there with rewards. I want everyone to get fair compensation for what they do. I just feel bad about getting better gear for less work than a smaller guild might do. A 10-man guild clears Sarth with three drakes has played better than I'm capable of right now and they get a Heroes' glove token. Moreover, Ulduar-10 is harder than Ulduar-25, which means that a raid really needs level 213 gears to do it. The gear gap between 10-person raiders and 25-person raiders is pretty noticeable. As promised, it is very nearly a whole tier of difference.
   Therefore I'd rather have unique sets in each dungeon size tailored towards the attributes that tend to be more important in that particular raid size. For small raids, survivability and mana regeneration/total mana might be the key whereas you might want higher damage output for the larger raids. It's not enough to adjust the health and damage values. Make the encounter feel different. Add lots of chaos for the 25s so it feels more on the difficulty level of the 10s. Give every one of those 25 raiders something to do.