Few quick things that have already been addressed but deserve repeating:
I wouldn't particularly care if 10-man and 25-man loot were identical. I don't think it's realistic to expect difficulty to be identical, because the difficulty is in your players and how they perform, not in the encounters themselves.
- When comparing 10-man hard to 25-man normal, keep in mind that the gear in 10-man hard was significantly better than the equivalent gear in 25-man normal. The ilvl being the same is misleading;
- 25-man hard content is more difficult than 10-man hard content;
- While ilvl expectations in gear allow it to be tuned that way, encounters with more moving parts that still depend on individual responsibility (don't get hit by Icehowl, etc) to avoid a wipe are still exponentially more difficult for a 25-man purely based on the increased likelihood for one player to make a critical mistake;
- Finally, organizing and recruiting for 25-man hard-mode raids is significantly more difficult than organizing and recruiting for 10-man hard mode raids.