20±20% normally means
What this means is that you should upgrade, because, for a while now, P2Pool's log is like this:
Pool stales: 9% Own: ~0% (0-78%) Own efficiency: ~110% (24-110%)
The "±" is not used for some time, so you have an oldish version and it's really not worth it to make any assessments based on a not updated version.

I downloaded it on Sunday from the first post in this thread. Where can I find a newer version?