Depends on the series of the amp.
All of them kill on the cleans but the crunch side can be quite different from series to series.
I once had a early Hot Rod Mod amp from the late 80's that was the same series that Vai used on blue powder and a MONSTER. Screaming gain super clarity amazing dynamics and was one of the best amps I have ever owned. I had some one offer me many times over what I had paid for it and my stupid self sold it not knowing what I really had.
Broke into the most amazing harmonic feedback you have ever heard it was like playing a real Train Wreck.
Here is a clip from my X100B in the old Church band no effects except a Delay and a Wah.
http://soundclick.com/share.cfm?id=4453782
The early ones were much lower gain and kinda stiff and hard sounding.