Hi Chris
I like the idea of having A & B axes.
But I worry about the layout of the electronics. I had a very compact box like that once. It was fine until it stopped. Then I found out just how hard it was to work on it! Verged on the impossible. OK, it WAS impossible.
My current electronics system is very much '2D' in layout. You can get at everything from above. Debugging is easy. Since my system has just had a total rebuild, that was a bit essential. Yes, total: replaced the USB SS with an ESS, added two MB-20 BoBs, replaced the old (dying) servo drivers with Gecko 320Xs, replaced the (spectacularly) dying SCR-based KBMG spindle drive with a MOSFET unit (much quieter motor but the RFI was incredible), and added some custom interface cards and opto isolators for the encoders and the eStop system. Getting a CRO in there was so easy from above.
Cheers
Roger