Pentatonic scales are incredibly boring to play. They're what guitarists use to sound good when they don't have the skill to play anything more interesting *coughhammetcough*. I stopped using them almost immediately after I learned them because they don't allow any room for interesting playing or experimentation. My advice to beginner guitarists, use them when you start out to get the feel of playing, but then learn to play in modes and my favourite metal scale, the diminished.
I've been playing guitar for a while now, I play reasonably well and have a pretty solid grounding in theory but both of these skills are merely tools to allow me to write music, which is my main focus. I've never been in a band and don't have any plans to start one, although I've almost written enough material for a full length, I'm working on arranging it at the moment.