#1
According to Wikipedia article on groove metal is say that solid state amps are preferred for this style, which seems differant from almost any professional musicians choice, is this true?
#2
Well Dime used solid state Randalls until he got his signature Krank
DO IT LIVE
#3
Considering just about the only prominent groove metal guitarist is Dime, who used solid state Randalls until he switched to Krank, they're probably just talking about him.
#4
I know I'm about to get flamed for this, but I never really liked Dimebag's tone. His playing was good, but his tone on most of the albums was pretty grating on my ears.

I'm going to guess that, if true, a preference for solid state amps just shows the technology of the time. Pantera (and to a lesser extent White Zombie and Living Colour) played guitar in a very syncopated, rhythmic fashion, often playing in the pocket like bass players. For this kind of playing, many solid state amps sound tighter. Not subjectively better, but tighter.

I'm guessing that these days, a Mesa/Boogie or other tube rectified class A/B amp would be your best choice. While they were around at the time, they weren't nearly as prevalent ... I think those amps may even still have been made-to-order at that time.
#5
I like the syncopated playing style but agree that it needs to be used along with other playing styles.