I've raced 19 turn 4 cell 1/12 scale for the last year. I have also tunned motors for a lot of racers in this area (100+), which has given me a good reading on the motors as I have dyno'd them before and after working on them.
Most can be made to work well based on the brushes, springs that can be changed. Out of the package, the Checkpoint is good, but so far the Komodo Dragon has been better. The only down side to the checkpoint is the lack of brushes and springs.
As to the Reedy Quad Magnet - get the Fantom motor, these have been great. I have also gotten the Atlas based motor to work as well as the Komodo. For a true Modified, I have several Epics that are balistic.
So Roar approved - Komodo, For true modified Epic. IMO