I have successfully done double-sided milling using VCare Pro and find it very easy to use the software for this purpose. For registering my X,Y coordinates I use bench dogs since my spoil board is a mixture of dog holes and dovetail slots. I am including a pic so you can visualize how It works. I did standard MFT 20mm holes spaced 96mm apart because I use other hold/clamping jigs not shown in the pic that benefit from the standard spacing but you could space them however you want. I say this because if you are doing something like a chair rung, the spacing I use is probably too far apart for a narrow piece like a chair rung. There are also lots of other examples all over the forum of ways to do your spoil board to be able to register accurately. I know Ben Myers has a file available that includes a corner registration ruler. Hope this helps. Best of luck to you.
I also considered the Parf II system. I made my original MFT tabletop for my assembly table using the dominofix jig which I don’t even think they sell anymore. It was ok and suited my purposes but the Parf system seemed much better…until I got my OF. It was a breeze to design the mft spoilboard and NO ENDLESS drilling required on my part lol. Regarding doing things like tenons, another option, depending on where you are in your table build, is to design the table to leave yourself the option to do vertical milling (see pic). I simply made the table top and spoil board in two parts (top and bottom halves) and have a stretcher running across the table to secure the vertical work piece. I am not done with this part of my table and want to add an additional stretcher with a dovetail slot to be able to slide my microjig dovetail clamps and also add some sort of jig for ensuring the piece is held square. As you ca see in the pic below my current method is less than precise and the wood being held by the clamps has some give so I’d like to make everything more secure. Anyway hope this gets your juices flowing and you can come up with something that works for you. Please share any brilliant ideas you come up with.
Winston Moy has posted some videos about double sided milling. I think he usually uses a jig and registration pins. I like the dog hole idea and will probably whip up a jig for my t-track if I need to mill both sides.
I’ve seen a few videos of the OF running in the vertical position. Has anyone toyed with the idea of being able to “lock” the table in the vertical position and laying a part horizontally on a jig to cut tenons?
My intention would be to make the modifications to a table similar to this (among others). Would it it be best to keep the opening through the bed close to one or the other Y rail &/or close to where the Y Rail is anchored? An example of a piece to cut a tenon on would be both ends of a 4x4 cross member for a farm table.