I have heard of guys definitely using both in the same pin... There was definitely a post on anasci or animalkits... both sides had a strong argument... If you are an advanced BBer using both, maybe you shouldn't be using GH subq anyway... it seems some of the mass monsters are using GH IV to maximize their expensive GH supplies.
Just some thoughts, sorry I can't find that post and link it for ya.. let me take another look though..