I found this read very entertaining, but it's basically summarized as followed
Full link here:
http://www.paragon.fi/articles/10-vs-25-comparison
" It's immediately obvious that there's a much greater degree of clarity and control in the 10-mans. Thinking logically, this should help quite a lot with the learning curve and avoiding mistakes, but that's not really something we could say our little skirmish 'proved' in practice. We already knew what the encounters were about and what the flame to avoid looked like -- relearning to accommodate differences is very different than learning from scratch.
A theme of more significance that you can clearly see in the three harder bosses for this tier is that the dps requirement is much too lenient in 10-man. This means that you don't really have to cut the amount of healers, which ensures relaxed gameplay for the healers while about half of their 25-man brethren are taking beta blockers just to be able to see clearly. The other half is naturally on the bench, sitting out for the extra dps. Perhaps this is a backlash from what we've been hearing about T11, but it really doesn't work as it is.
Proper tuning has repercussions though, since class balance has a huge impact when you're forced into two-heal and solo heal situations. And that's not even a stretch -- don't be surprised if you see a druid solo healing Ragnaros 10 hc before this tier is over. Might or might not happen, but at least it seemed plausible enough. Try doing that with a shaman.
This leads us to the fact that the gap between an optimal setup and the wrong setup seems to be quite a bit larger in 10-man than in 25s. If the encounters are really hard, you'll need a proper setup. Guilds shooting for a world first should always be expected to come up with one, but those below, the ones without alt raids, will be left hanging. If the encounters are tuned for the 'average' setup, guilds who can afford the optimal one will steamroll through them.
If we were really playing 10-man, we *would* have a close to optimal setup. Even right now, scaled down from 25 to 10, we would have about 14 players and 30-ish fully raid-capable characters. The difficulty and tuning we're concerned about is for that scenario, not for the level where you're simply enjoying the game with the hand you've been dealt."
So it's clear that raid composition becomes increasingly important, especially when you compare it to the 10vs25. My thoughts on this though, is Blizzard making these encounters intentionally easier for min/maxing while increasing the needed awareness from individuals? Previous tiers there were fights that were most definitely more difficult in 10 then 25, however this tier does not seem to be the case, give or take a particular phase of a fight. I'd like to hear some opinions why or why not this may not be the case.