This is not worth $350 for just 2 stepper motors, worm gears, and an aluminum frame. And I doubt the Solidoodle Nema14 motor will handle the weight.

Pros: Dual 'hobbed' wheels working together to push material harder and faster.
Uses worm gear for 20:1 gearing for higher torque. I would think retraction would be halved at worst.
Simple addition to make dual extruder (not at same time, motors need to be reversed for second extruder).
Smaller footprint than Wades (not a hard thing to do).

Cons: Double motors and possible double drivers (or over-heating issues). They look like high current NEMA14, so more expensive.
Probably heavier. I would think that you defeated the purpose of higher speed extrusion with making the extruder heavier causing issues with your X movement.
Price: The link shows $350. Seriously? You can buy an entire Mendel kit for $350 from geeetech.

This is what you get when a mechanical engineer gets involved. I agree that a higher torque extruder helps, but why not use a single NEMA23 (cheap) with bowden setup? Why not engineer a solution to the bowden problems and remove the weight from the head? And why two motor solution? If he is a mechanical engineer, why not design a single motor pinch design? Bleh, rant over.

Looks promising

http://www.3ders.org/articles/20130822- … nters.html

Can it still retract with that set up? I'm a little skeptical.

http://www.3ders.org/articles/20130822- … nters.html