Ignoring and forgiving the standard slow glam song on the albums, Pantera has been nothing but speedy metal along the lines of a slightly less poppy motley Crue from 1985-1990. The 1983 album was fucking horrible and is better left forgotten It's not like they switched from being a def leppard/whitesnake clone.
The first song Down wrote (that we know of based on teh first NOLA) was written in 1991 if i remember rightly. The promotion and material of that album can hardly be considered sellout especially since they had a major label release it and a platinum seller fronting it. The content was definitely not accessible as far as MTV TRL kids fallin in love at first listen
Superjoint was also jamming as early as 93-94 at the same time as Phil was messing around with his Black Metal fascination with Christ Inversion and later Viking Crown (which he was doing in..........95...memory again)
Phil was also friends with Killjoy of Necrophagia for many many hears and wanted to work with him for a long time. He played guitar on their 1999 release.
I think Phil is more the kind of guy that wants to be seen as the metal hero of the little man instead of a multi millionaire Pantera frontman.
I'm pretty sure I'm close on these dates anyway.