Basically this mod is like the "soldering the shunt" modifications of common shunt-current-sensing controllers; it makes the controller unable to measure what's really happening, so it can't protect itself (or other system components) from overcurrent.
Everything could work perfectly, but only if the controller is well-designed and all the components involved are capable of much more than the controller specification limits.
Since it's very common for these controller manufacturers to use the cheapest parts they can get away with, as close as they could possibly be to the spec limit of the controller itself, then any mod that goes over those specs risks component failure. How bad the failure is depends on what component it is and how it fails, and the circumstances it fails under.
The benefits you can get depend on the motor you are using, and the rest of the system and the situation; if you're basically potentially doubling the phase current (since half of it is passing outside the controller's ability to monitor), then if that pushes the motor far past saturation, then you may get more heat out of it than extra power, depending on motor design and the conditions it's under at the time.
If the motor's not near saturation, you get more extra power than heat, and could be worth doing, as long as the controller itself actually has parts that can handle it.