Re the Felder router spindle, I thought of that as well, along with the extra RPM available from a VFD. But you're still stuck with swapping cutters and setting depth.

A quick change spindle, combined with a simple CNC control and preset tools, would be awesome. I've thought about the same sort of thing. But for my use, it would really just be a nifty toy. The time and money would be better spent on a CNC router.