The business account comes with unlimited history of deleted/modified files, so you can recover anything that once was on Dropbox.
On my Macbook Pro, the "average battery impact" (last 8 hours) as reported by Activity Monitor is 1.2 (not sure what's the unit, but it's a low value compared to other apps), and we use it daily for work so it's kind of active the whole day. I wouldn't call it a CPU hog by far.
1) That's good to hear about unlimited history - however that wasn't the issue in my case - the files either didn't show up in in the history anymore, even though it clearly wasn't past the grace period, or the showed up and reported an error when trying to open them. So the last I checked, there were non recoverable states in Dropbox and I therefore would never trust it as the only backup (and neither should you).
2) The CPU hog thing is very inconsistent - it probably doesn't affect all OS version/hardware combinations or they would have solved it since long ago. All I know is that I regularly see the client go to 80-100% usage of one core for a rather long time, meanwhile taking forever to sync just a few files - which clearly shouldn't happen in an application that mostly does IO. There are probably certain file types it has some problems with, but I didn't have the patience to analyze it yet, I simply switched to SpiderOak.
On my Macbook Pro, the "average battery impact" (last 8 hours) as reported by Activity Monitor is 1.2 (not sure what's the unit, but it's a low value compared to other apps), and we use it daily for work so it's kind of active the whole day. I wouldn't call it a CPU hog by far.