This is awsome! I don't think I have the skill/patience to modify one quite that nicely...
For me, my first step would be to buy the mill and the CNC conversion would be later. I do however, want the option to be able to do it. But my little X2 just isn't rigid enough for some of the things that I do. I'd like to be able to use a face mill. Right now, I use a small flycutter and it works okay, but I have to take very small bites and it quite honestly scares me. I also seem to have trouble using mills larger than 1/4" as they start to chatter and the whole machine seems to be in disagreement over the operation.
Mind you, this was my first mill and I've learned a lot and have enjoyed it, but I need something larger without going all the way up to a floor model as I don't have the room. My bench is big and sturdy and can support a small turret mill or square column - I'd just take over the space where my X2 sits now.
Another thing that I like about the turret mill is the belt drive. The gears in the X2 are loud and I'm afraid they'll give me trouble. Plus, the whole head assembly gets very warm. For that reason, I've been leaning toward a no-gear head for my next mill. Those square column mills are all gear heads.
Mark