Re: Musa velutina hardiness.
I had a small mat come back for me this year after a winter low of between 6F-11F in Knoxville, TN. Our official low was 11F, I think, but I'm in a bit of a cold spot and am quite a few degrees colder for winter lows. Didn't use any protection either, except for maybe an inch of mulch. I would think that you should have great success in your zone 8b!