First of all, thanks for doing the work to put this guide together. I could have used this info way back when. Excellent way of organizing the information, too.

I think molexing assemblies is nice but in the long run probably overkill. IIRC, in 26 playfield swaps I have had to repair one assembly after the swap, and that was a drop target coil so I had to desolder it anyway. This is over a 12 year period. There just aren't a whole lot of things that have to be reworked again to the point of removing an assembly. Most people just don't put enough plays on a game in home use to wear anything out. If you like working on connectors, there will be plenty of other original connectors that will need to be repinned during the playfield swap, you can be sure of that. To me, this additional step just seems like a personal preference, time available thing.

One more thought, don't forget that each new connection creates a possible failure point.

Why bother predrilling the bottom of the playfield? I certainly understand drilling holes on the topside and do that on my own swaps, but underneath? Unless you are seeing some splintering it seems unnecessary to me. Make sure the dimpled holes are marked well, use a good driver and it shouldn't be a problem.

Maybe dial the torque down a bit on your driver? Especially if some are stripping out on you. Do you use the old screws or replace them with a hex head screw? IIRC, EK uses Phillips heads on most if not all of the underside stuff. Did a swap on my EK back in 2004 with an original NOS playfield, so it has been awhile. I replace the old screws with new hex head stuff whenever I can these days.

You could try running the screw in nearly all the way and finishing with a nut driver or screwdriver by hand. I understand that it will take more time that way.