The current ones with the Eternal Classic voicing sound great judging from the two I've played, I can't say that all of the older mod versions sounded as good, I've played some I really didn't dig much, but he's really dialed in a nice sound now with the Eternal Classic and the mark VII. The 16 or so extra holes he typically drills for the main mods is of course pretty invasive by the standards of today, but if something is already hacked up a bit I guess it doesn't matter much and back in the day no-one cared about the state of their old Marshalls anyway.
His stuff is fairly common-place here in Sweden, he must have done hundreds of mods since the late 80s not counting the much smaller tweaks he does to a lot of amps. The absolute godfather of mods over here, for sure, basically synonymous with amp mods - and I've been eyeing some of the single-channel Eternal Classics myself.
