Advice: If you want 10 man HC to be tuned close enough to how 25 man is, be on PTR for the 10 man normal modes and esp for the heroic modes tests. It's the only way Blizzard gets enough feedback to tune decently enough to not have to overnerf.
Internal testing tends to miss some glaring bugs just because the testers know exactly how the mechanics work (may sound stupid but I've had it happen a ton with my tests on my own software) and subconsciously avoid being stupid with the encounter. A raider will always be stupid with it - either by trying to not die on a wipe or simply trying to get the most info possible out of the tries.
10 man has a good chance to get a much much better next tier if they have guilds testing the encounters, like the top 25 man guilds do. Add some top guilds forming and getting their own strats (not basing on the 25 man videos) and launching videos and 10 man hardcore guilds should start developing nicely.