I mentioned before that my rigger is similar in size to the predator.
It is brushed powered on Ni cells ( good ones)
There are no rear ride pads, ride shoes or call them what we like. I was told that on brushed I need them, well that is BS !
Straight shaft riggers can work. However I reccomend that you try a wire drive ( very low cost ) or a flex to get the appropriate thrust angles.
Get the CoB / CoG correct and the appropriate sponson angles and you can make a brushed rigger get up and go, just ask Jay Turner and Ed Hughey to name a few.
Plastic props CAN work.

Here is the deal. With a well built home made rigger running a brushed can ( stock or above ) on 6 x Ni cells ( good ones ) you can make a rigger boogie !!
It will not take out honours at the next LA saw's but you will have fun with it. I DO !!

Design it.
Build it
Run it.
I do.