for the 1000000th time, why arren´t you a member of Porcupine Tree? :)
Well, in essence, I am a "member" of Porcupine Tree, I am a "touring member". The band lineup expands for live touring, but for the writing and recording process, they have no need for the extra guitarist, or the extra creative input.
So it is really about what works best for the band....and in the live setting, I am a part of that unit.