Sadly this will not work, so I have still no solution 
I run into this issue. What is what I expected as the motor step firmware part needs a good performance at this place, so this can not be implemented for motors.
Kevin answered this once on a similar issue here:
I have encountered a second problem:
[extruder_stepper extruder_sync]
Will not sync the settings as pressure advanced. This also means the motors are not completely in sync as move instructions will be calculated twice. This can wear out the timing belts, similar to a car with all-wheel drive and differential lock in curves, would wear out the wheels.
Somebody with a new idea?
Currently, Iām close to solve this by a hardware step/dir bridge hack, as Iām running out of ideas.