My 46 powered trainer also uses an 11-5 prop. I had been using APC props but, while very efficient, they tended to be brittle. My main gear is only 5/32" and pretty springy. A less than perfect touchdown and I was nicking the tip of the prop on the runway. I have a bunch of 10.5-5 props now!

A club member suggested changing to a Master Airscrew prop. Not as efficient as the APC but they can survive a mild prop strike without as much damage. Of course, learning to land better will help...