I elected to go with NEMA 17s for the torque and for the commonality with existing Wade's/Greg's. Originally I had designed it with 14s, but after further research I was afraid of reliability and speed issues due to the lower torque. The size/weight vs speed doesn't seem to be an issue for the x-axis motor (probably thanks in part to the low friction v-slot extrusions on the i3v) and I haven't had a single problem in about 100+hrs of printing with it. I'll put files out soon and will probably try to sell the hardware by itself in addition to the whole extruder.

More info on the design, etc here: http://www.flywheeldesigns.com/blogs...-i3-prusa-easy