I'm more positive on the JVM than most here.
Does it stack up to a vintage 2203 or 1959? Gods no. But it does sound good.
I do think it sounds way better than the new DSL series, too though.
I've never had one under a mic, though, so I'm not as well versed as I could be. I guess for what they cost there are just better options. For a couple grand (new) you can literally find a beat up 2203 if you look hard enough, so I suppose the benefits just don't outstrip the opportunity costs.
Not to mention if something goes wrong, you are absolutely shit out of luck - just like with any super complex PCB amp. With that being the case, it narrows down the prospective JVM fan to mostly younger or newer players, it seems, that don't have as much experience with amps.
If I got a great deal on one, I would certainly try it out though. I think they sound good from what I can tell. Just not 2 grand new good. Especially when there are so many great amps on the market in that price range.
For gods sake theres a bogner helios 50 for 2 grand in the classifieds right now.
The prices are coming down on them used, and if they keep coming down, I may try one just to try it. Mic it up and see what's what.