I've handled a number of KBD75 at meetups. It's an excellent board for first build. Affordable, but sturdy.
The KBD75 is only a 'tray-mount,' but it seems to be on the high end of that . I find that switches in general feel good in the KBD75, whether it be tactiles or clickies, especially BOX clickies. As I said, they are sturdy.
They are really, really heavy, and are clearly meant to be a desk-bound build, so keep that in mind. I find that the WKL versions are more pleasing to the eye, and appear less cluttered. There is a KBD75 variant available in Canada, here on this board, the PLA75.
They can even be silenced fairly effectively. You can look up the video of a Silent Alpaca KBD75 build on Youtube.
The weakness of the KBD75 is the cluttered layout, with no 'blockers' for spacing. Very 2016 in concept. As you saw, KBDFans tried to remedy the problem by developing a spaced 75% called the Bella, but it had the stupid cat/dog-faced switch-opener, so people didn't buy it. It stayed up for days in the in-stock section, recently. Too bad, because it's probably a good keyboard without the dog-thing.
I sympathize with your desire to avoid a 65% layout, as you will have to use layers and stuff. TOFU65 is great, though, and can be silenced. KBD67 mk2 is better, and the new KBD67 lite will be cheap.
I don't know much about the edges of the KBD75, or the LED, but I see many people with active LED strips on the KBD75. The amount of light is limited by the design. Which is fine with me. I don't know anything about the polycarb or non-metal KBD75.
As for TKL, I recently acquired a KBD8X MKII in polycarb, and it's all you really need. I was going to get a metal-cased one, but they were OOS. My polycarb 8X is flawless, though. That's not something everyone can count on, sadly. The sound and feel is amazing, but I am using an aftermarket polycarbonate plate.