Theres some good things and some bad things to this change.
The bad :
- Balancing nightmare, 1 mc --> 1 mage --> 1 sheep. 3 mc --> 3 mages --> communication chaos and etc etc.
- Unless 25 man gets more than 20% of the players in loot (over 5 tokens) it wont be worthwhile.
- The big scale of which you think a raid is will be reduced, therefore the potential epicness.
- Some classes/specs behave better in 25 man than 10 man.
- Extremely big loottables in 10 man making it hard to get specifick items?
The good :
- Core guilds just got a whole new meaning, finally that close group of 10 man who carried your 25 man can work together
and achieve the loot you deserved
- Gear inflation stops , no more full 25 man HC gear in 10 player modes steamrushing.
- More flexible to raid, if 25 man on, you raid that, if not you can always get nice gear from there.