Lens sample variation is real: thirty plus years ago, when we were picking lenses for ground truth photography at NASA, we'd get Nikon to send us a dozen lenses and typically found two-three of them matched the required specification, based on the published specs for these lenses. (For scientific data, the requirements are MUCH more stringent than for general purpose photographic use ... Typically, 11 out of 12 would be just fine for normal use.)
I've been scanning film since 1984, for work, and then for personal/exhibition uses since 1995. I have one dedicated film scanner left—Nikon Coolscan V ED— and will not replace it when it dies. A high resolution copy camera approach is the right way to go now.
For production work, don't even consider the notion of doing this without a copystand or other dedicated camera stand setup. It's a waste of time. You need a GOOD copystand, a GOOD light box, and a GOOD fixture to hold your film flat and registered accurately to do high quality captures. I use a Novoflex Magic Stand copystand setup, with a Novoflex focusing rail. For print captures, I have Color-balanced LED lights that I set up with light stands and use a Sekonic L358 meter to balance the lighting evenly and eliminate shadows. For negative captures, I've been using a home-made film carrier/guide until now. I just received the Negative Supply 120 Carrier device and ProMount ... expensive, but superbly made and extremely robust, precise negative holders, essentially. When the Nikon dies finally, I'll buy their 135 Carrier too.
For a copy camera, a good quality FourThirds or APS-C format camera with 16 Mpixels or greater is fine for most of what I do with Minox through 6x6 format negatives. I've used my Olympus E-M1 quite a lot, both with their ZD 35mm f/3.5 Macro lens (with and without the ED-14 teleconverter) and with my favorite old 1969 Micro-Nikkor 55mm f/3.5 lens. Both return very high quality results, although the square format captures get down to about 9 Mpixel with the E-M1.
Switching to the Leica CL (24 Mpixel camera) nets a newer sensor with more dynamic range and a 16 Mpixel capture of 6x6 format negs. That's a healthy improvement. I use it with the superb Macro-Elmarit-R 60mm or Summicron-R 50mm lenses, both with superb results. (Turns out the Summicron-R 50 actually outperforms the ME60 when I go to greater than 1:1 magnification, for example, when capturing Minox negatives at 1.7:1.)
Looking at the larger format negatives primarily, I've now set up the Hasselblad 907x/CFVII 50c with the V-system Makro-Planar 120mm or Planar 80mm lenses and tested copy work with them. The results are just phenomenal, better than I need: for square format capture, resolution is up to 39 Mpixels and detailing is just plain mind blowing, plus the net when shooting raw with this is 16 bits-per-pixel depth ... That's about 14 stops tonal range effectively (the best I can get out of the Leica is about 12-13 stops). It's a super high end setup, but eh? I have it, and I might as well use it for as many things as I can dream up to get my value out of it. 😀
Good luck with your endeavors, Chris!
G