To clarify my view on how Hard Modes/Normal Modes have worked so far:

OS/Ulduar: Triggered Hard Modes, I agree with other comments that to even get to some of these, it's a gear check, but the lack of flexibility in having both Heroic and Normal saved to the same Raid ID was pretty limiting. While the 10 man "Hard" mode group I'm in did work our asses to get our proto-drakes, it did sort of suck that we couldn't help out other guildies working through normal 10 man Ulduar since were saved already.

TOC: Pre-Raid Toggle, was very flexible as I stated above. Allows a group to focus on Hard Modes, knock those out and still be available to help out other guildies get through normal. Obviously, it'd be great if every guildie's gear level was equal all the way through an expansion. Unfortunately, that just isn't the case and you always tend to get that core group of hard core raiders who are there every raid and do hard modes, etc and gear up faster. TOC allows that group to still be available to help out in normal runs and make raids full guild runs versus having to pug a few open spots (NOT that there's anything wrong with that!!! lol). The fact that you only have so many attempts in Heroic mode is also a plus as the "Tribute" aspect of it is a nice touch IMO.

ICC: Per Boss Toggle, while details are still sketchy, if you aren't allowed to run both on separate Raid IDs, then we're back to Ulduar/OS inflexibility. Yes, it's more "clear" that this is hard mode, but honestly, I don't think it was that confusing before (i.e. 4 towers, No elders killed, Big Red SHINY Button pushed, etc). With this per Boss toggle, does this mean a raid can just bang their head repeatedly on a heroic mode encounter with no consequence? I liked the limited number attempts in Heroic TOC and hope it stays in ICC somehow.

Meh, maybe I'm just qq'ing too much, but I do hope there's some flexibility in ICC where you can run both normal and heroic in different Raid IDs.