It seems pretty obvious by the design that these will very much increase the strength on the arms. Currently there 6 screws. 4 of those screws mount the motor to the lower plastic arm. The other 2 screws are where the problem exists. Those 2 screws are recessed and hold the top plastic and the bottom plastic together. That recess area is very light plastic and the torque by the motors "WILL" crack the frame in those recessions. It's just a matter of time.I'm happy with mine screwed AND glued... Arms a super strong. No issues. Did 8 flights took off strong arms to see if cracks were continuing to increase or perhaps new ones.
It seemed to do what it is intended to do. Whether it's because of them or them and the glue job who knows...but all is well in my world...
The UAVBits uses all 6 screws to bolster and strengthen the 2 frame screws. It has plastic that fits into the recesses of the screw holes and provides support. No doubt this provides a lot more strength.