Excellent review! Thanks.Don't buy the Core, buy one of the OneBlade Hybrid refurbs, they're close in price, but use the stainless Genesis head. I tried the original Core, and then waited for the updated model a couple months later, and ultimately returned it back in 2017. - There's now a V2 (if you call the ones I used V1 and V1.1 or V1.5), which might have addressed my gripes.
When I tried the original(s), it took work to get a clean/close shave, compared to my DEs. The other thing I didn't like was the plastic head didn't seem to glide as smoothly on my face as your typical metal head razor, that's the only way I can describe it, not harsh, not the blade, the Triton head just didn't seem to glide as easily with some soaps. There was as some minor concern about accidentally cutting off the front stops, which were also Triton/polymer. - Keep in mind there's apparently an even newer revision, and this was the original and then the modified original. There's a 3rd version that uses a slightly different head compound, which is touted as being stronger.
I've purchased a refurbished Hybrid ($119) using a discount which brought it down even more. Having showed up yesterday, I used it this morning, once I found the left over blade from 2017 (they forgot to include the 10 pack of blades), it shaves both closer and much more smoothly, with better glide than the either of those Core models. Actually, it shaved pretty darn well, and that's coming from somebody who loves their Timeless 95 OC, Gillette Slim, Rockwell 6s, and Schick Adjustable. - I managed a two(2) pass shave, that equaled what I'd have gotten with the slim using a Feather or Nacet blade, but very quickly and easily. (You can just zip this thing around, pressing to engage the pivot). I think the Hybrid is definitely a keeper and I liked how well is managed those 'trouble' areas, the two small scars, the sides of the jaw, and upper lip. No sting from the witchazel or aftershave, and my face is easily BBS feeling.