For the past few years I've dutifully cut down everything after the first frost, but this year I am not going to cut any of them.
As far as I can tell, the only purpose that cutting them down serve is to make them look "prettier" in the winter.
It makes sense to me that if no one goes out in the wild and cuts them down, then there is no reason for me to do so either.

This winter I will just let the frosts brown the leaves up good, then I will squish them down around the stems to help protect them.

I have a multi-trunk M. basjoo that soared to about 13 feet this year, and there are plenty of leaves with which to mulch the base (last year I didn't bother to mulch at all, and (possibly thanks to our mild winter) the plant came through fine).

You hear advice to save as much of the trunk(s) as possible, building a cage around them to fill with leaves, but the one time I tried it there was no difference - all the growth came up from the base after the trunk was largely mush.

I figure I'll cut way back in April after seeing new sprouts.

So far it looks to be a good idea. My banana plants were still pushing new leaves at the top of the stem until the beginning of January! A series of hard freezes since then seemed to have slowed them down, but even then, it looks like the central part of the stem are still alive.
True, the leaves are brown and tattered, and completely limp hanging down, but this did help to protect the stems from cold winds.

I think I am going to wait until the temperatures stop going below freezing at night, then I will cut the old leaves off.

Considering that I was getting new leaves pushing at the top of last years stems mid winter, I'm thinking it was a good idea to leave the stems standing instead of cutting them to some arbitrary height. I think this will result in having a bit head start on them this Spring.

As of Mid March 2013, I have cut off the dead leaves and checked out the tops of the stems of all my banana plants (heights from 3-6 feet tall) and all of them have bits of green leaf showing.

The outside leaf sheaves on the stems are brown and cracked but the inside of the stems are still alive.

So basically, my experiment apparently was a success. This year my banana plants will start pushing new leaves at the same point they stopped late last fall!
I am excited to see how they will do this year having such a major head start.

The lowest temperature that I saw here this past winter was 18F on a few nights so it was a relatively mild winter.