I heard somewhere that some models of the eee burn quite a bit of power in S4 sleep (suspend to disk/"hibernate"), so much so that it's not much benefit and S3 sleep (suspend to RAM)...

Could someone quantify this a bit?

I'm wondering if, with an upgraded 32G SSD, suspend-to-disk/hibernation is worth the power saving while off. Or is it even reliable? Then again waiting an additional 20 seconds to suspend and 12 seconds to resume (the write and read times of 1GB RAM to my coming upgraded SSD) can get annoying where S3 takes just a few seconds...

Some models have been reported to draw power when *OFF*, similarly with hibernate. If your eee draws power while off, it will be dead within a week from a full charge. If this is not the case (just check overnight, you should be able to tell right away), then it won't be the case with hibernate either. This is, btw, not a standard feature, but a faulty battery/mainboard issue.

My eee burns about 1% battery per hour in sleep, I've left it on for about 5 days asleep and it was still alive when I turned it back on (from a full charge).

I do notice that in S3 sleep, my 900a does take a considerable amount of power from the battery, 1% per hour seems optimistic for my machine. Then again my battery doesn't nearly hold as much as a 901's battery.

Though I haven't checked the 'off' power, has anyone looked into this "feature"/misdesign? I wouldn't mind finding a soldering iron fix to fix it...

I'd stay as far away from a Li-ion with a soldiering iron as I could, but maybe that's just Sony's fault I've only seen that "feature" complained about in a couple other forums, I don't have hard data or anything. I'd expect some batteries/mainboards to fail, and that sounds like a reasonable way, so I believe it happens.

As for the 900 battery size, you should be able to get a pretty good idea of charge times and whatnot if you check out the actual charge:The 901 is a 6500 mAh battery, I think the 900 is 4400 or 4800 mAh. BUT: only something like 90% is accessible (Li-ions need residual charge to not explode), which means you should get ~3500 mAh, or ~2/3 of a 901, so you should see more like 1.5-2% drain per hour (all else being equal). If it's taking more than that, you need to run powertop, and possibly get it repaired.

I have the (tiny) 4.4Ah battery. Was thinking about re-celling it with 2.8-3Ah cells to get a boost to 5.6Ah to 6Ah once the 2.2Ah cells no longer provide adequate performance.

I just tested my eee around 8 hours with it in 'off' (S5) and unplugged - looks like it's still at around 100%, not nearly as bad as S3 where I'd expect around 10% usage.

It might be worth it trying to use S4 if I can stand the suspend/resume times, hoping hibernate (S4) is about the same as S5 (off). Just that it'd mean 1GB of swap...

10% for 8 hours sounds pretty good. I never got hibernate to work, even with a 2 GB swap. I got it to go down, and even that took forever (2 min, maybe?).

I guess ultimately it depends on what you're doing with it. I use mine pretty much every day, so I just leave it in S3.