I think at least the extruder needs that.
To add to that, nema17's are way easy to get, you can get a 1.68 or 1.7 amp version, they have 2000grams/cm torque if I remember it well.
Why don't you ask 'the guy' or ask it in the topic where this model is discussed?
Heres the wiki:
[
reprap.org]
And I quote:
Quote
Note: This image shows NEMA14 stepper motors rather than 17 but they don't work - not enough torque. Will update once 17s are installed.