Trying to choose a kit, need some advice.

I'd like to know this as well.

 

It's pretty much six of one, half dozen of the other. Propulsion and member size are the same on both. The only real differences are the number of wheels and the Z-axis configuration. The greater number of wheels on the Workbee will wear better so that would be the better choice for the hard core user intending to turn out mass quantities of work (etsy vendors, etc.). But for the hobbyist, the Sphinx is more than adequate and not something you'll likely wear out. The other difference being the Z-axis configuration. The Sphinx has more actual working depth than the Workbee but as the installation order of the plates on the Workbee can easily be reversed to make it similar to the Sphinx this is really a non issue.

 

I see there is a high torque motors option on the Sphinx. Does that not make sense on the 60 x 40 workbee due to it being belt driven?

 

If you want the higher torque steppers just decline the motors on the machine build page and add them from their page in the electronics section.

Depends entirely on how you use it/what you intend to cut.