nema23 I would also say are overkill for pretty much any 3d printer, except maybe if you are lifting a fairly heavy solid bed - I could see the Z-axis benefiting there. If you have spare nema23's lying around anyway then of course no reason not to use them.

I was actually toying with the idea of a servo driven 3d printer using small 100w servos or similar for X and Y, could be a fun experiment if I can find some cheap enough.