The "source" for the TGTBTU 4K remaster was simply far more problematic w/ all the various problems already baked in that Kino attempted to undo -- and there's really only so much anyone can undo of those various problems w/out yielding too many/much new/more problems (that might make the...
As I noted earlier, it seems like FAFDM comes from the same prior KL BD master, except they apparently recovered/restored/added ~30secs of previously missing footage as noted by another poster as follows...
AFoD, OTOH, does look like a different/better (re)grading/(re)tweaking/master (that now...
10-bit seems a waste for SDR if limited to BT.709 anyway. There should be no benefit at all near as I can tell.
https://www.richardlackey.com/choosing-video-color-space/#:~:text=709)-,Rec.,and%20therefore%20the%20same%20gamut).
Your PJ making use of upto 12-bit is a diff story since it should...
For A Few Dollars More looks like the exact same transfer/master as the previous KL BD, except in 4K, but w/ no extra detail. Unless you had issues w/ the encode/compression of that prior BD, don't see any reason to upgrade to this 4K, if you already have that BD -- and the old MGM BD may have...
Fortunately, we don't have to rely on them alone... especially the Beaver's, which probably offers the least reliable/useful ones around (at least amongst the better known sites anyway)...
_Man_