Best Linear Track Design for a CNC Machine?

I'm not trying to suggest that Stepcraft completely overhaul their basic design here 😆 , I was just wondering what users consider to be the ideal solution for engaging the moving assemblies with the tracks on a theoretical CNC machine. Stepcraft's brass roller solution doesn't seem to be optimal either for a self-assembly CNC machine kit or a turnkey solution.

I.e., if you were to design your own 'ideal' CNC machine, what solution would you choose? My ideal machine configuration would not have a larger XY footprint than the 2/840 machine I already have. Myabe a little more Z axis travel would be useful, but I don't need much for milling guitar bodies, necks and other 2.5D parts from plastic or aluminium.

For the Y axis in particular, I was thinking of a central ball screw/ball nut for the linear drive mechanism coupled to one powerful NEMA stepper motor (at least a NEMA 23) with a rack and pinion either side and a locating bearing with some built in float at the opposite end. The ball nut would be mounted at the centre of a rigid axle, probably within a housing with aluminium tube sections either side would suffice to keep the weight down.

Would this be subject to alignment challenges do you think? I guess it depends on the rigidity of the transverse axle and amount of pinion tooth engaged with the track.

I see from a quick Google search that the EZ-Mini from EZ-Router.com operates with a rack and pinion drive on both X and Y axes:

http://ez-router.com/products/cnc-router-systems/ez-mini.html

Has anybody else designed and/or build their own CNC machine? Possibly not the best forum to be expressing these ideas or asking these questions on is it? I guess www.cnczone.com is better but I'm not about to join yet more forums right now, my digital footprint is already far too large. :ohmy:

Doug