The JPX has the most open and full tone. I think the chambering plays a part in this. Tone is still tight, but the chambering gives up a hair of tightness. The JPXI is uber tight. Extremely tight and focused. Brightest of the three. The JP12 is a mix of the two. Really doesn't give up much in the tightness department, but the tone is warmer and rounder. Honestly any of the three are versatile enough to do pretty much anything.
Thank you very much
I recently bought a jpxi 6 and i absolutely agree on the tightness, it's absolutely awesome and it sings incredibly even on solos.
I think my next will be either a jpx 7 or a jp12 7, just to change a little bit