There has been no indication yet of any difference to the 72v version and any other version of this motor.
I run a HBS36 at 60v and so far so good.
Upon my work with inductors I've found you can use the motor as a type of buck converter by limiting the PWM width to the motor.
I have found the higher voltages you push into the motors windings, if the motor winding and core size are not enough for these higher voltages more heat is generated by the lower resistance windings and in a moment the voltage saturates the core with magnetic intensity with little or no gains to MF. More winds can convert the flux field intenisty into magnetic density. either or both can saturate the core leaving no room for either to give an more gains. The core can only present so much reaction to the current and voltage.
Observation over a coil and switcher with different taps along its turns yield identical voltage at each tap and more current was available the shorter the tap was from source. To turn the voltage into magnetic intensity (throw or K) one must make sure some rules are adhered to for it to remain efficient at top speed.
The stator in the motor is based on transformer electro-mechanics with a iron core. And its said around an iron core 6 enamel wire turns around a former for every 1.2v is a good guide to get the most efficiency from any winding. The thickness of the windings decreases the resistance and increases the current available for magnetic density (torque).
When you stray too far from the basic rules you lose efficiency and the top speed gains are not easy to attain when you overvolt too far.
With my 60v overvolt am lucky to get an extra 20kph for the extra 24v, but any extra over 10kph from the hubs normal top speed takes a good chunk of capacity from my pack.
My HBS36 has 34 slots between two phases that make the circuit when operational. If I run 50v PWM pulses into 34 slots divide 50V into 1.2v the the product of that into 34 slots = 1.22v per slot times by 6 turns = 7 turns per former.
With the same equation for a 75v supply I would need 10 or even 11 turns per former to convert the voltage into MF.
At 75v with 34 slots and seven turns on each slot, each will exceed the rule above by .6v and over 20v for 34 slots.
Without knowing resistances you can take a guess that a 24v overvolt will probably cost you an extra 5 amps and bring the efficiency of the motor down to an average of 25%.
All ball park figures here.
At best the motor runs at 85% efficiency now running at 60% efficiency, 40% of 5 amps at 20v can reach 60 watts of power wasted. This is what I approximate my losses are at full throttle with the 36v hub at 60v.
If you have the power to waste for an overvolt like this then it would be fine. But I feel overvolting has only so much to be gained, if done right and limit the duty cycle of the PWM a bit more distance and a bit more speed one travels is the target of such a pursuit.
It will work and probably well too, but it's no magic fix and you may find yourself cutting throttle voltage a little to make it worth while