[Hero, G2 Touch Android Development] dkelley:
sure, thanks for asking.

this is unscientific - and I don't have time to measure or compare battery life over days or even hours at this point.... BUT here goes:

- froyd 1.5: turn off data/bgupdates/wifi/bt (which is how I sleep at night), battery doesn't budge sometimes, other times it'll drop 1%/hr. either way pretty great. with 691 OC it eats battery fast with cpu-hungry apps/games. Also background music playing eats battery in this rom, doesn't seem to clock down to minimum cpu speed needed even with screen off. I suspect this could be improved a lot with a different configuration during screen off and maybe a much lower top cpu speed with screen off... just a theory however.

- floyo 0.8: currently my favorite (sorry hacre, just waiting for some of those magical fixes to responsiveness there buddy :-). It's pretty much CM6 but fully working... what most people are looking for from the nightlies but will never get (more later on nightlies). It's excellent - great battery life, still runs very well at low clock speeds (low being stock speed for example, no OC right now on my phone). it has a VERY snappy ui. same criteria (all connectivity disabled except phone) gives me 0%/hr use while I sleep, sometimes as much as just under 1%/hr but typically 0%. Obviously it's not 0% in any of these roms, but so low as to display as 0% in juice plotter fwiw. Music playback still uses plenty of battery but is as low as I've seen so far in froyo. Gameplay battery life is slightly better than Iv'e seen so far. Oh yea - this is with his BFS kernel fwiw.

- I don't currently touch ele's froyo builds since his builds are amazing but have that odd random slowdown from hell thing going on. I had it in two different versions of his roms after previously loving his roms. VERY pretty roms, but then so are froyd roms with all those themes. Meh - if it works for you without slowdowns then it's a terrific rom. Doesn't work for me. So no battery life report on current version therefore.... but I got 1% to 1.5%/hr use with all connections off while sleeping in 1.8. Which is fine. I don't remember how battery was with screen on etc though. I think it used slightly less battery in music playing with screen off than froyd did though.

- cronos: well, HWMNBN can put together some damn good roms, like his style or not. 1.2.0 is a very good froyo rom. Very very good. I had some glitchy video playback with it - he's always messing with video performance, unfortunately it always seems to result in issues I don't get in other roms LoL. Otherwise it's similar to floyo but wasn't super good for battery. it was just ok. 1.5%/hr while I slept, and unfortunately I foudn it's overall gameplay performance to be lower than that of either froyd (which was obviously fastest) or floyo (which was a pretty close second to froyd). And I'm talking 518mHz with froyd and floyo and 691mHz with cronos. But Cronos was super stable and very snappy in the UI. Until Floyo came along it was a good contender - but imho floyo does what it does better. And cronos doesn't include cmsettings. so you're hooped for configuration - live with 270o rotation at random moments or go to a different rom. oddly one of his theme builders integrates CMsettings in this theme haha, so that's a workaround at least.

Nightlies: I can't say about this nightly since without it grabbing my ext partition apps I just wasn't interested in trying it out. also I need stable video recording - strange but true, it is a requirement for me. But this is a nightly - I'll try to make this more clear this time. Nightly builds are not "hey, let's keep building until we get closer to a releasable build" in every case. they were like that for a while in this case. But since roms building off CM6 for hero are getting working camera, working video, and so on and so on that these nightlies have broken - well that should tell everyone that the nightlies here are actually either a different branch from the candidates other developers are building from (hacre, erasmux, and other builders such as HWMNBN, elelinux).

Either a parallel branch with the same ultimate goal (a solid stable froyo for gsm hero), or a branch that has moved past the release candidate builds those other guys are building off of which would mean that these nightlies contain future experimental code.

Either way, it's very clear after all this time that these nightlies are not built with the intention of being daily use roms. They're built because there is a timed build on a certain repository - if it works, great. But don't count on it :-)