In watching a few videos it seems like Joe B's hands are big enough that he can keep his thumb at the top of the neck anyway. Slash seems to go to the "rock star" pose with the neck almost straight up in the air. That would seem to use the weight of the guitar itself to your advantage. From what I've read, it seems that I would eventually get used to it. Given the amount of time that I (don't) already practice, that might be a while.

Of course, a pastor friend of mine moved to North Dakota. An older lady in the congregation gave him this beautiful Les Paul that had just been sitting in her attic. I'd probably make time in that situation.