Honestly, I'm ashamed to admit that I didn't even think about the steppers. I just measured them (with a meat thermometer on the outer casing) after around 2 hours of printing and got the following:
X- axis: 71 deg C
Extruder: 67 deg C
Ambient: 27 deg C
From what I've seen online, people seem to recommend 80 deg C as an upper limit for the steppers. So it sounds like this should be ok?
I haven't printed ABS with this system... I'm not too keen on the fumes. But with the elevated bed/extruder temperatures for ABS... I'm wondering if I would need a stepper cooling system. Do you have experience with this?