Also realize that said about SRV can also be said to the same degree regarding Diana Krall. I'm talking about the "all too often" bit. (While she does nothing for me, she is not bad, far from the worst I've ever heard. However, that is personal taste).
I do agree that classical music is recorded with far greater care than any other genre, even jazz. Heck, it even sounds good on regular old CD in most cases. (I don't think I would want to hear it in MP3 though). There are some good prog rock recordings done with care (if one looks to the good remastered editions it can be even better), not quite as much as classical done right the first time, mind you, but some prog rock groups do care about what they are doing. Unfortunately, when it reaches the hands of the remastering engineer often times those guys either do what they want regardless or whatever the record company wants, forget the artists who labored and cared. Some examples of good ones for testing would be certain Pink Floyd cuts, Rush's Moving Pictures also comes to mind as well. That said, no, I would not use say something like Snakes & Arrows as a tester for example.
Yes, most rock is recorded like crap with the rule of thumb being "let's see how loud we can go and how much clipping we can get away with". So yes, I personally would not put all my eggs in that basket or any one basket either, even classical. Not because classical is not best suited, we have already established that it is well suited, but more because I like to throw the kitchen sink at systems or gear and I like to use stuff I am familiar with every note on and that includes some classical and across my broad range of genres. That way it's far easier to tell if something is off, even subtly. On a revealing system it is easier to tell if it's the recording that is off too (and I've had a few surprise disappointments with my system of recordings I thought were fine that were really so awful that I threw them out because I could not stand to listen to them to even try to find some redeeming quality).
Again though, this is all a personal preference thing and all good at the end of the day.