I may have to listen more to the suggestions offered here on the forum (or perhaps listen better ...)
Another test, this time with a 2"x2"x6" piece of Yellowheart. I rounded off the corners with some custom gcode (like Gary did, but using the edge of the cutter) then ran a roughing + finish toolpath to make this shape. It took 25 left-to-right-to-left passes to do, about 15 minutes. During the cutting in 'lathe mode', the router sounded good and steady, no evidence of abrupt digging etc. The tool was moving up/down slowly to distribute the wear across 0.5" of cutter edge.
When stopped, there was a lot of tear out on the extremities. The finish on one side of each 'bump' was very good (the top side of each in the photo), the lower side was rougher, not good enough in my view. But the tear out was clearly unacceptable.
So again, I should compare this to std wrapped machining, but so far the combination of moving cutter+moving work is ... underwhelming.
As others have suggested