I know I'm going to sound like I'm tech inclined but I'm not. I'm a player through and through.. It's due to being frugal, having too many amps (mostly vintage/all Fenders) I bought a used Bjr (I still don't know when it was built) reworked the tone stack, the phase invertor, installed a Hyboar output transformer and a Mojotone reverb pan, aftermarket speaker. Went through a few speakers since, some that I tried led to the "box tonality" I've read about. Had a Eminence CRex is for a long time, (IMO good speaker for a Bjr) after experiememnting with an old Oxford 12T6, I dropped in a Sica/Jensen Ri C12Q and I'm very pleased with it. (speaker gives that classic Fender chime & handles OD pretty well)

I've read the IV has similar mods.

For me, overall its a nice, its done a great job of extinguishing any gas I have for a boutique 1x12

I've gigged it (not a lot) imo it handles a stage pretty well though. Definitely No complaints.

I've gigged several Fender PCP amps over the last 2 decades and have decent results. I'm convinced its all in how I treat them.

A) I never move the amp till its cooled down
B) I never expose the amp to extreme temperature.
C) Treat the amp as a fragile hi-fi piece of equipement.

It's common sense but that translates into letting the amps reach room temp before I move them. I warm up the car before I transport them, I don't transport them in the trunk or where they will rumble around, I don't bang them off doorjams or walls as I enter Bars, I don't tug on the chord halfway accross the stage/room like its a garden hose (I use best practices like wraping the chord around the handles, then plugging it in)

The welds and traces on all PCB amps can be subject to oxidization, lifting etc.. minimizing condensation/oxidization from extreme tempeture changs or harsh jolts when cooling down, all this has served me well when using a modern Fenders.