I'm running C3 at work and have C4 pro at home. Yes, there aren't a lot of obvious diferences, but I do find that now that I'm used to C4 at home, I'm feeling frustrated by the lack of features in C3. C3 is VERY stable compared to C1, and you can do a LOT with it. I'd really recommend making the jump. Then, if you decide to upgrade to C4, you'll have an upgrade path to jump from. Good luck!