It will be interesting to see how you feel after getting back into the unit. I still have my RP500, and in general I find the 11R more enjoyable to play stand-alone. Sounds more real, more inspiring, all that stuff.
However, recorded with both in a mix (say 11R left, RP500 right, similar tone/gain) the RP seems to dominate and have more balls for lack of a better term. I think it's just a little more compressed and that tends to make it stay out in front better. I'm talking about lower gain stuff similar to REM or southern rock type stuff as well. Just my opinion.
And you can get real nasty tones that I don't think are achievable with the 11R when getting creative with some of the pedal models (gonkulator, etc). Those are fun to play with too.