They are outstanding. IMHO.
I have a friend who SWEARS by them, hell his whole studio, and P.A. are powered by Carvin amps, he's got some that are probably 25 years old, and says he's never had an issue with any of them.
I like mine and know alot of people who really like them as well, I would recommend them.
Although for guitar rigs, depending on what your running and trying to achieve, SS vs Tube.... like I said depends on the results your trying to achieve.