Re: The cold hardy list
I'm in zone 7a, and saw 8F last winter for my absolute minimum low in my yard (12F was the official low for Knoxville I think) last year.
Both Musa cheesmani (covered with a bag of leaves) and Musa 'Royal Purple' (just a little extra mulch) came back for me here.
Orinoco came back, right against the west side of the house.
Musa velutina is very variable (I've killed it bunches of times!), but I think Randy has the best, most cold-hardy variety I've seen yet (and the largest).
Musa sp. 'Yunnan' came back in March!
From what I've seen in Anniston (zone 8a):
Musa balbisiana is pretty hardy (the form that he has anyway).
The Musa itinerans variety he has down there (suspected to be var. guangdongensis) is very hardy, with the pseudostems not freezing down to the ground.
Musa mannii comes back in February down there! It will bloom there also.
Musa coccinea returns, but doesn't bloom (yet anyway).
He has others that shouldn't survive, but do anyway (Dwarf Cavendish, a plant that looks just like Jamaican Red, a wild Musa acuminata, etc.), so I don't know if that's a fair observation or not. It is a nice microclimate there at the museum.