Michael Hedges was a very tasteful guitarist. He played mainly acoustic fingerstyle guitar and was very lyrical in his music. He played mainly instrumental music although he did sing a few songs (about as well as Satriani did on "Flying in a Blue Dream"). His first album was "Breakfast in the Field"...I tell you this guy is classic. Search the internet for him and I'm sure you'll find some info on him. Unfortunately he passed away a few years back before the majority of the guitar world ever got a chance to hear him. I would suggest giving it a listen.

As far as Dimebag...Pantera...chops monster...a severe lack of musical theory does not restrict his playing. In fact, it only frees his music up because of the lack of theoretical boundries. A true riff master!