I tried bigsister, but gave up. Lots of stuff that could not be made to run reliably, if at all. BS is nice, once it gets to the 1.0 mark. For now, I would use nagios over it any time.
I did not look at BigBrother, that might be a good alternatice as well. I also only played around with nagios a couple of days, but found it pretty well suited to what it was designed for.