I have 4.07 of Aquarium with Rybka 4.1

I use aquarium for analysis/blunder checks of my correspondence games. I keep my interesting and annotated games in a database. I use XFCC play as an interface.  And on occasion I look up games in the database for historic games.

My question is, given my use is it worthwhile upgrading to 2011? Would Chess Assistant be a better purchase?

Thanks in advance