Hi all, wanted to share my experience between the two versions of this TV. I've tested both the M557-G0 and the M658-G1, IE the budget 55" and the better 65". I used identical SW settings between both panels copied from RTings. Some observations after running them side by side(I'm at a novice at this stuff, be gentle):
-The M557-G0 definitely has worse contrast, and the difference is pretty significant in dark scenes. When running the a local dimming test on both at the same time the M658-G1 had inky blacks, whereas the cheaper variant just looked like a very dark grey
-The M557-G0 version also had more of the dirty screen effect, immediately noticeable even on the UI home screen
-The M557-G0 also had what looked like mintor backlight bleed in the top right corner of the screen, M658-G1 had none
-The M658-G1 colours were warmer, which I preferred
Packaging wise both were identical, same remote, same accessories, etc. Build quality is the same pretty much, although it felt like the M658-G1 was nearly twice as heavy as the cheaper model lifting it up.
I'm returning the M557-G0 and sticking with the 65" in the meantime. It's unfortunate that Costco only sells the cheaper one, I would have preferred to buy my TV from them.