I haven't played a Plexi. I've played an original JTM45 and I've played a few late 70's JMP's. I have a friend from school who actually became friends with Malcom and Angus and he told me that despite their access to any gear they wanted, they almost exclusively used Plexis. When you closely listen to Malcom's rhythm tone, it is amazingly clean. It usually has just a little hair. I love that tone, and that is what I'd be after in one of these amps.