Taking another look at what was occurring to create ratty edges, I noticed the gap in the fence, right where the drilling is done, allows for the unsupported end of the board to move. As you move through the mortise and the board contacts the other side of the fence, the mortise slot stays pretty true.
So I did a "tune up" on the machine and chisel bits. I honed the exterior chisels on a water stone to 8000 and used the included cone sharpener to sharpen the inside. Then I took two milled pieces of maple and used them to sandwich the board so it can't move front to back. The next mortise was much better but not being satisfied with better, I took a mortise chisel to it and cleaned it up. The mortise looked pretty good. Next, of course, is to set up the tenoning jig. Once completed, I created a tenon and the fit was excellent.
And after all this was done I had to ask myself, "Do I really want to make 40 frame and panel doors and drawer fronts using this method?" There would be no profile on the interior of the rails and stiles - Mission style. The doors and drawers I am gluing up today for the island have a Shaker profile, but the island is being finished differently than the carcases on the rest of the cabinets so that's no big deal. They were created with a Shaker router bit set. And I have that rail coping sled that works like a charm. And I've got the dust collection at the router table really dialed in well.
Hmmmmmm........
The easiest method is to use the router bit set. I've got everything I need for that. The only down side is I'll have to accept getting only one rail/stile board from each 5" wide board I have. But I have enough wood. The cut offs I can use for panel glue ups.
I think you can guess which way I'm leaning.
“Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain