Since motor speed is proportional to the applied battery voltage, there is an extra margin built into V5 motors to allow them to maintain predictable 100% of rated speed even with lower voltage of a battery in discharged state, while still having some usable torque.
I don’t know if the latest firmware of V5 motors applies software limit on the output speed, but older motors could easily spin up to 110% or even 115% on a fresh battery with direct voltage set to maximum and minimal load.
Not really. As you get closer to 100% of rated velocity the max torque available out of the motor decreases, because it is proportional to the difference between motor back EMF and applied voltage.
And, since output power of the motor is a product of output speed * torque, it goes down when you are approaching max speed.
It looks like for V5 motor the peak power output under load is somewhere around 60-70% of rated speed:
So when you are not pushing something heavy and just need to accelerate and run fast - you could approach max speed, but you will use the battery power at lower efficiency:
Wdym? The Space Shuttle flew at 104% most of the times. 