Adding to this, I also have a Transcend ECC kit of G-Die, which uses a variant of the B83 PCB. These should be 8-layer, and I'm pretty sure the Samsung OEM dual-rank PCB used with G-Die is, too.
They do not have the same 1t weakness on 4-dimm boards as dual-rank B63. Unfortunately, they are still slightly RTL-weak, albeit less so than Samsung OEM. I can't say much about subtiming weaknesses because these are the only sticks of this model I've found so far.
42/44/4/4 also passed SP32M waza but forgot screen, needed <2v. 42/43/4/4 stopped training at about 2750mhz, maybe bclk up in OS is possible. I haven't tested on the Impact due to weird efficiency issues I haven't solved. Also, I still need to test whether they can run >2800mhz.
(12/23/2023) I should have another 3 pairs on the way, so maybe some quad rank or mild binning will be possible. Also, I think that's a large enough sample size to check for frequency ability.