The low voltage jacks are still able to produce 100% torque at all RPMs.
The torque is a function of phase and so long as the phase is advanced far enough you get torque.

I can't argue about the low volts causing heat, however that'd be why companies like heinrich offer 48 volt jacks and 92-106 volt trucks.
Sadly NMHG is far far behind in this area, but we have recieved warnings about 96+ V units in the works.

In fact this is an area where ALL north american brands lag behind... but it's coming

BT's here in NA have been AC for a bunch of years, but they are simply rebadged heinrichs. I can attest to the speed, strength and durability of those reach trucks.

Abusing any electric truck will cause heat.
But I'd rather have a unit kick into thermal-cutback, then burn comms and brushes.

The Z series AC electrics from shyster are the fasteset, tourqeyest (sp?) units shyster has ever made. As long as you shut the 'economizer mode' off.(other wise they are real dogs :-) )

The shear number of wear items in a DC motored truck mean way more maintenance, period.

Every brand is AC or converting, so soon you won't have any choice.

It's just my humble opinion and I'm sorry if I offend.
I've worked on electric jacks, reaches, forklifts for 20 years, and the future IS ac.