I still utilize one in my 2.1 system in my office at work. It's certainly not the greatest performer, but for the $100 I paid for it from Newegg is does a nice job. Plus I always liked the design styling of the synergy subs which mates well with my Klipsch XB-10s.
As far as how it will perform with your RP series depends mostly on the size of your room. But I can guarantee that it would be in your best interest to save/budget for an upgrade down the line as it will certainly be the weakest link in your system.