Well, on our last Disney trip, DH was about 340, and he's only 5'10" so the pounds probably look bigger on him than on your taller hubby.
He could ride everything, but sometimes it was a bit interesting sitting next to him wiht a lap bar. I didn't really feel that secure, and I, sadly, was not that tiny either!
It also has to do with where he holds his weight. DH looks like a sumo wrestler, with very muscular thighs, and that added to the lap-bar issue, because if he had little chicken legs but a bigger belly, he could have put the lap-bar down further. As it was, it had to stop where his legs started. But a smaller-legged bigger-bellied person would have a less-cramped, perhaps, time.
But anyway, DH went on everything he wanted to.
He just told me that the most uncomfortable ride was Dumbo, but we did have three of us in there. ON the other hand, I was tens of pounds smaller on THAT trip (see avatar for my in-retrospect-perfectly-acceptable size then), and DS was only 1 at the time.
And he says he didin't like how he felt on Indy.
But still, he went on everything he wanted to go on. Which was almost everything (except Splash, b/c I was the only one who wanted to do that, so DH and DS went on Pooh three times in a row).