Re: anyone else here able to grip the ball w/ one hand and not the other?
Yeah I think that's pretty normal for non-NBA freaks. In fact, even a large portion of league guys clearly have a looser grip on the rock with their off hand. Every now and again, a guy like Carlos Boozer will come around though who can use each hand just as effectively.
Me personally, I'm 6'3'' and can only palm a basketball with my right hand on a nice humid day with a fresh indoor (or rubber) ball. I tell ya, it'd be a heck of a lot easier to dunk better if I could palm a rock.