I liike the JSX also, just not as much. I had one but I sold it and bought another XXX. If big, downtuned sound is your thing, you might like something else, but I find it to be the crunchiest thing going. Tons of usable gain, tons of chunck. I use one in my extra room at home with a baby Marshall cab(turned very low of course!) and it sounds killer.
Also, has anyone noticed that the effects loop on the xxx and the jsx are active even when there is nothing plugged in? Turn the amp on and play with the send and return and you'll see what I mean. Without the footswitch. Now plug the footswitch in and when you activate the loop, you can crank the send and return as a boost. Bypass the loop and you are back to normal.