EHM2, great post and I fully agree. And like I said, I am keeping the 45MX with the intention of getting another one for student work. It's certainly not a POS and had worked fairly well for me up until the point I put the 45S head on. I still do not know what happened to make it to where I could not align it but at times, depending on height, it was way off, like lift the baseboard an inch off the lower structure to get it sharp off, really bizarre.
Those slick adjustable lensboards would have worked except for two things.
1. It would not have worked with a 150mm F4 Apo Rodagon N as it will not fit and the rear lens cell is also rather large for a enlarger lens, pretty critical.
2. If things are set up correctly and there is no structural kludging going on, you really should not need it so I think you are essentially using using "Fix a Flat" instead of actually fixing the flat.
The usual size I print is 16x20 and 20x24 from both 120 and 4x5 negs using an f-stop that is between one to three stops from wide open. I could get away with the depth of field you cite at F/11 with an 11x14 print, but not in using my preferred sizes and methods.
The Saunders is not perfect either, little things like having to replace the carriage lock knob with one that won't split and not being able to see the contrast setting between burns when doing a localized contrast change are still less than ideal, but I was not after ideal, I was after having more easily controlled consistency. In my opinion in using an enlarger to make prints in a professional production arena, being able to have consistent results that directly reflect a desired input is essential.
Up to this point, I spent more than half my time in the darkroom aligning the enlarger with every neg and head position change. That is a ton of time that I could have been doing other things like making more salable prints, being outside shooting, spending time with my wife, etc.
I am keeping the kit, will set it up again once I have a proper workspace that I can actually move around in and it will be fine. I am sure I will do some mods to it just like I did with installing the variable speed fan in the 45S head, I enjoy that so when the time is right, the enlarger will be right.