Is this really a good idea?

From what I have read about hummers, they need to go into a low-metabolic-rate torpor every night, and cannot survive if the weather gets too cold at night.  I don't know for sure what makes them decide to migrate, and wonder if food availability might have something to do with that.  I do know that my feeder typically has a few nearly constant patrons just before migration.  They just sit in the nearby branches and take turns feeding and occassionally chasing each other (and the Chicadees that like to drink the water out of the ant trap).  Then, they are gone.  I have left it up for a few weeks after that, and sometimes I see another hummer for a day or so, but then, nothing.  I suspect that the late ones are just passing through from farther north.

I guess that a hummer that can find a warm spot to roost for the night might make it through the late fall and even early winter with a feeder as a food source.  But, don't they also need insects for protein?  And, since any warm place is almost surely produced by human activities, is it assured for the entire winter?  What about electric power outages, winter vacations, etc.?

I know that some migratory fish species have been attracted to human created warmth, only to face mass die-offs when the heat is not constant during cold weather.

So, I am wondering if leaving the feeders up too long could induce some (probably young) hummers to stay too long and lead to their deaths.

More knowledge?  Thoughts?