I'm getting about 1%/hour to 1%/1.5hour on CM7 with the same setup that gets 1%/1.5h-1%/2.0h on stock 408, so it's slightly worse then 408, but not by a huge amount. All times are at idle and with the same apps installed.
Cant comment on MIUI, havnt tried it.
On a side note, it will still be a few weeks until I can make a repack since my pc is pretty much dead and I have finals coming up.
If you already have CM7 installed you wont be missing much at all, just use the zips I've linked to previously and you'll be fine.
When I do any new users can skip installing them as most of them will be pre-installed (except gapps, for CM you shouldnt bundle them directly)
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Nexus 4: Stock JDQ39 (4.2.2) Nexus 7 Sucessor: Waiting for it
iTouch 5G: Stock 10B146 (6.1.2) Venue Pro: Stock 219-33 (7.10.8862.144)