I finished to first two tests in my prototype conch and it is very promising. Let me say first off that the conch is nothing more than an inexpensive ice cream maker. I put a heating pad cushioned by a pad where ice would go, and set the whole thing at a 45 degree angle. Also, as most ice cream maker motors are only for intermittent use, it is plugged into a 24 hour timer that turns the motor off (but leaves the heating on) once an hour for half of an hour. It has run fine for two batches now, three days at a time. The lesson from the first batch was two fold:
1) Don't use powdered sugar. The cornstarch combines with trace water and with the application of heat, thickens the whole mixture too much.
2) You don't need powdered sugar. This was a major surprise. Apparently 2-3 days at 110 F with trace water around dissolves the sugar and that portion of the grit is gone.
Thanks to the advice of Frederick of Dagoba, I added about 200 one quarter inch stainless steel balls to the second batch. In effect this made a ball mill. A day into the conch/refining I checked the batch and it was just starting to smooth out the extra grit. I then dropped the motor and that experiment ended, but I would call it a partial success.
So give it a try. Get a $15 ice cream maker, a heating pad and some SS balls and you can give refining a try.
Also, I made a neat discovery about hiding the "grit flaw". Just take your chocolate (go ahead and conch it, but don't worry about the refining portion, i.e. no balls) and add nuts, fruit or even some ground coffee to the batch. The texture of those items completely overshadows the chocolate texture flaw and no one but you, me and everyone here will know how you made such great chocolate.
Give it a try and let me know how it goes.