Well, I must be doing something wrong since I run these NEMA23, rated at 3.0 Amps (!) with no issues - once I stuck a heat sink on each driver of the xPro, a fan to blow over them and tweak the few GRBL parameters :

Dual Shaft Nema 23 CNC Stepper Motor 76mm 1.9Nm 23HS30-3006D - US$ 21.38

The steppers are running cool, myOX can work for hours upon hours with no issues - drivers not shutting down from overheating.

Maybe it's like those kids who have tuned up stick shift cars ? I can pull next to quite a few of them in my Town&Country stock minivan, front wheel drive, automatic. Light turns green and I just about smoke my tires (fronts of course), leaving the kids and their fancy tuned cars behind. Sure, they tend to quickly catch up and pass me. They just don't know how to drive and probably have slow reaction times. In theory, I should not be able to do that ... at all ! Yet, in reality, I do ...

So why should I spend 129$+ on four fancy MOSFET when I can get an entire controller for the same price ?? Especially when that controller does the job just fine.

 

Stepper motors powered correctly run about 40-80 Celsius when but will run fine upto 120. If they are cool all the time they are underpowered.

I suppose it could comes down to the finish your looking to achieve if you are infact able to maintain steps. I have posted a video of mosfets powering 4.5a motors at 1.3a. The same xpro drv drivers I tested were not able to achieve the same smooth motion that the motors are capable of with the mosfets at just 1.3a. Infact I welcome you to post a video of one trying to compare.