Well, not a lot if you're happy with your sound. The POD has 32 amp models, cab simulations, and onboard effects. But, like I said, if you're happy with your sound, you could use the direct out AND mic your amp giving you a nice fat sound maybe panned 80% right and left.
From what it sounds like, you don't need a POD. But, you might want to check one out anyway just to be sure. Do you use the Floorboard? That's the only reason I went with a POD rather than the J-Station. I was really interested in the acoustic modelling the J-Station does but I need the Floorboard for wah.