I tried a search and found a few threads about prop adapters of collet and set screw types.  Given a motor with a 5mm shaft would a collet or set screw type adapter be best?  Assume a virgin adapter and only one use.  I realize that the collet type can gall if they spin or come loose, and may not be reusable.  Flats are commonly used with one set screw, also needed for two screws?  Would you switch to a collet type, if you like those, even if the motor comes with a flat on the shaft and set screw adapters?  Is there science or anecdotal information?

I'm using collets and have had no trouble so far.  

Yep, Collets work for me.

I like the collet because you can tighten it so the prop will slip or come off if the plane noses over. No prop breaks since doing this.
Bob

Good point Bob.

Nothing but collet, every time I've tried using grub screw type prop adapters, they usually end in an offset shaft, and hence vibration issues.

The good thing about a collet is reduces concentrically.

Buy yourself a battery terminal puller to get off the tight ones though!

I didn't even know that a puller was made. That's going on my next rcdude order. Thanks Crist. The few times i needed a puller I have used a battery terminal puller. I'm using a tru turn E Spinner on the SV22 so the collet is part of the spinner. Voltron may have a custom collet on it as I'm going to do a front mount on that.