How to quantify the difference in power of tablesaw motor rewired to 240 vs 120 volts
I don't know who is saying those comments or in what context they are saying, but I don't agree.  If the motor is actually designed to be jumpered between 240V and 120V, then it should perform the same in either configuration. 

Induction motors of this type have an entirely passive rotor, so no brushes.  The only windings are in the non-moving fields, so it is practicable to switch them. How it's done is to wind the fields with 2 wires half the cross-section.  For 120V, those wires are connected in parallel. For 240V, in series.  The same amount of current flows through each wire in either configuration, so motor performance is the same, and temperature will be the same.  

If you are abusing a motor that is not manufactured to be switchable, then all bets are off.  Or if you are dealing with a brushed or shaded-pole motor on a smaller appliance, the rules can change, but that is not OP's question.