I thought the clips I've heard sounded pretty good on that Studio 900.
I go to a big hard rock and metal club pretty often and recently talked to Erik from Stephen Pearcy's band. They have 900s there and I think they belong to the club but most bands use the power amp.section and run some modeller or preamp into it.
I dig my Silver Jubilee Studio and glad I didn't get the other models instead. The Plexi seems too loud for my use and this has a bit more gain than the 800 if I heard that correctly.
Cool amps, made in England. I'm sure the JCM 900 Studio will sound better than an actual JCm 900.