Frank, I covered my yellow banana with just a sheet the last two nights. It saw temperatures of 28°F and 30°F without foliage damage or any damage to its flower. As you say, it seems to be a very tough banana! I'd like to see it used much more in the landscape.
I will be updating this thread with new pictures each week as the flower progresses.
In addition, I have updated the Wiki page for musella lasiocarpa:
http://www.bananas.org/wiki/Musella_Lasiocarpa
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Austin
Arkansas River Valley
Average January Low: 31°F, Average August High: 92°F
Extreme Winter Lows: 5-15°F, Extreme Summer Highs: 100-112°F, Annual Precipitation: 52 inches