I think it's a wise decision. Nobody would be surprised if it is the last JP album ever so it would be a shame if it sounded mediocre like their last albums. Nostradamus was complete failure and while Redeemer wasn't bad musically, the sound was pretty awful.
Andy will make them sound heavier for sure, I don't know if Tom Allom will have an influence on the sound or will just sort of frame the artistic content. That will be interesting.