I like enabling absolute zero sharpness under video tweaks to avoid any ugly haloing in H.264 video but I don't like that it overrides picture style sharpness when not recording as this makes LV Digic peaking a little less effective.
I'd rather push this one step further: if we are not recording, or we are in photo mode, we can actually maximize the sharpness on standby for the purpose of focus peaking.
There are some other registers that may help: http://www.magiclantern.fm/forum/index.php?topic=2403.0
Unfortunately, most of them (including the sharpness trick) only work on DIGIC 4.
I used to rec h264 in a flat way, like Neutral preset - 2 - 4, but I use to set the viewfinder with the standard Faithfull to get the sharp.
There are some interesting investigations to make more flat the presets and get more dinamic range: http://www.magiclantern.fm/forum/index.php?topic=16299.new#new