I have never tried the GFS charcoal, I will have to get a bag and see if I like it.
I've been a KBB guy pretty much all my grilling life, no problems to date. Just saw several of the Kingsford "other" bags today and almost filled trousers at the prices! It's freaking charcoal, Hoooo Eeee! I might try a bag for a feast.
Granted, on this site I feel a bit like a rookie but, deep smoke product isn't my biggest priority, my brother is the smoker for the most part. I am a roaster, straight product direct/indirect process guy. If I'm not at the airport when my ship comes in, I will be jumping into the WSM pool but, when one has the ability to shut down the vents and save half a load of charcoal and use it for part of the next go round, KBB has served me well.
I am also a bluegrass musician and WSM means something completely different in my first thought!
I have to say, for a new guy here, I am learning quite a bit about how other people deal with some of the same issues that give me pause.