Well, I've had tons of "oh shite" moments with my Mesa 2c+...
about ten-ish years ago, I bought a Marshall DSL 50 combo at a guitar center. They also had that Mesa in there, and they were both going for $750 (obviously, the c+ was used). I picked up the DSL thinking getting a new amp would be better, etc (lol) and when I got home, I googled the c+ and all the praise it got, blah blah. SO, I returned it the next day and got the c+ instead.
It's been a love/hate relationship with that amp for the longest time, but now it's ALL love. I took out the amp and made a ghetto-ass enclosure for it and bought a 4x12 for it (sounded pretty good, I suppose). I sold the combo it came in with the speaker for $200 (bahahahaha) to some guy I knew. I don't feel bad about karma at all, because that dude is a HUUUUUGE douche.
Fast forward some more, and I'm thinking of selling the amp. I can't ever get it to sound the way I want it to. I decide to try to make it work some more, and I get a Port City 2x12 (super awesome). The sound is much better, but still not ALL the way there. Bought a Rane PEQ (best EQ for an amp, ever) and DAMN, that really brought shite to life.
About a 6 months ago, I managed to break the tube socket while I attemped to install some THD Yellowjackets (sounds super dumb, but the pins were too big for some reason). As I call Mesa to figure out where to repair it, they tell me that I can send it in to be looked at by Mike B. himself, AND that I can upgrade to Simul-Class / EQ if I want.
So, I did. Now, my amp rapes things. I suppose this is a story of what COULD have been my biggest regret, but it panned out for the best :p