Interesting concept,seems to mitigate some issues of the MPCNC. The Z Axis assembly looks a bit on the weak side, especially for heavier spindles. I see the most problems in CNC builds here,tbh - the Z axis is far more of a problem than the other ones as it tends to destabilize itself due to the lever effect it does suffer from.
BTW: In terms of Google: Why not put the file on something like Github/Launchpad,etc. so others can contribute,comment or fork it?
The issue with the Z axis is not only the slider but also the threaded rod. Just a few thoughts/experiences on it based on my experience with the MPCNC and various different changes to Z axis group people made:
rigidity of the axis is paramount. When the router moves it does move toward the material. If there is not enough rigidity the material will push the router bit away variably and an angle is created which then exercises pressure on the router bit, creating enormous loads and usually kills it - which is bloody dangerous.
The other issue is the weight of the spindle. A makita RT0702C is around 2kg, but has its drawbacks. A water cooled “China spindle” weights around 5. That is, from my experience, too much for one threaded rod.
Don’t get me wrong, your design is great and imho you are onto something - it removes a lot of other issues the MPCNC has and might be the perfect middle ground between “MPCNC” and “full aluminium build”. I like it a lot for this.