I used to ride in some snow bibs I got from my neighbor (up though last season, actually. I just got a brand new pair of regular snow pants for this year, can't wait to try 'em out). They were never in a million years meant for snowboarding, and they still fit over my boots, so I wouldn't worry about that.
One thing that I will miss about the bibs is that I tend to work when I ride, so a lot of times I don't even wear a shell, just a t-shirt and flannel, and I would wear my bibs over my flannel shirt to keep the butt from getting wet and freezing (not very comfy). I suppose I could go for major geek cred (I'm already there, don't worry!
) and tuck my shirt into my snow pants. So, there's a thought for ya.
I'd say go for it. I think I may miss those suckers a little bit after a while.