I just sold my V3 (kinda sorta), I had it for over a year. Sounded great, I originally had one of the first run (always a possibility for problems regardless of manufacturer) for a few months and it did have a problem. The replacement has been running without a hitch for over a year though. Most Carvin amps are reliable regardless of what people may say. The TN100 I've heard has a lot of issues, but I've seen several Carvin amps go for 10+ years with no problems. I have a Legacy, and it's been going strong for about 6 years now. The guy I'm selling the V3 to gigs every weekend, blasting the amp at 7 Master, never overheated or anything. Small transformers? I don't think so :? I'm sure Mesa's are heftier, but Carvins are just fine. Carvins are factory direct, if they sold in stores they would sell for about 75% more than they currently go for, don't believe the "it's cheaper, it must be crap" thing. Carvins have their own sound though, so you may or may not like it. I do, personally.
Anyway, the V3: they're VERY picky with cabinets. I was running mine through a 4x12 loaded with BR12s. There's a little fizz, but it's definitely not a week sounding amp. It needs volume to sound full, I used a G-Major in the loop to turn the amp up and turn down the output on the G-Major, that worked well. It's a completely different sound than a Recto, so don't expect that. It's more mid heavy, will do it's own "chugga chugga" thing and still sound great for solos. The amp needs a lot of tweaking, but just about any tone you could ever want is inside this amp.
The reason I'm selling mine, is because I wanted something with a different "feel" to it. The V3 has a good feel, just not what I'm after. It's hard to explain, touch dynamics and all that good stuff. Try one out, you might like it: it DOES take a lot of tweaking to find your sound though, keep that in mind.