My musa basjoos were successfully over-wintered to about 2ft last year, and they ended up close to 14ft at the peak, but frost is imminent within the next few weeks so they will be going dormant pretty soon. Here's the documentation of the growth all throughout the year.
21 April 2012: I successfully protected them up to around 2ft, and they are already getting up to 4ft within a week.
Left plant