I think the Pod Pro has an effects loop and the Pod doesn't, correct ? That might be a big deal to some people. I like the option of putting time-based and modulation effects like chorus, flanging, pitch-shifting, and delay after the preamp.
The one thing I like about the Bass Pod(same shape and size of the Pod) is that it is small and it can sit right next to my recorder and mixer. That makes it easy to hold the bass while sitting down, and reach over and adjust the Bass Pod, trim controls on the preamp, and the faders on the recorder. If I had the Pod in a rack all of that would be tougher to do. Then again, you don't have to put the Pod Pro in a rack.
Question for Pod Pro owners, do you like the effects and do you use them ? I have played the thing in a store but was just curious to know if you found them good. Which ones in particular do you like ?