Interesting concept. The lack of Z is a killer, but the good news is one could make a riser fairly easily for the vertical column. It'd take a pretty big chunk of CI, but I suppose aluminum could be used, preferably 7075-T6.
Personally, I wish they would have simply ignored the horizontal mill portion, and improved on the mini-knee mill concept.
The thing I like about it... I'm guessing the added rigidity would pay dividends. The large column cross section is significantly beefier than a mini-mill. Also, I think it'd be a decent candidate for CNC.