Brushless setups are more efficient, but not 5min --> 45min worth. As Campy said, you'd also need LiPos. Of course, you can use LiPos with your current motor and see a big increase in run time just from that. Take it one step at a time, and spread the $$$ out.

Is your current setup direct drive or geared? Just going to a geared setup can increase run time, as you can use a more efficient prop at a lower RPM.

The trick to avoiding bending the motor shaft is to try avoid those 1 point landings . I don't think a brushless setup is going to be any less bendable.

disclaimer: I'm not an electric flight expert. I have done a little of it, and some research as I plan to get more in to it, but there are lots of guys who know a lot more than I do, that's for sure.