MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
Funny, I made a similar thing (didn't had time to post it)! Your's is nice.
And I agree, it improves a lot the Z axis (mine was always falling down, due to slip on motor shaft).
Now I plan to put the motors at the bottom, maybe by using the top part, and make a new one there (with a bearing).