And that's for Micron b-die not Samsung that was being discussed? I don't have first hand experience of clocking either but from what I've read e-die seems to be a consistently highly binned IC, whereas for example Samsung b-die has the potential to clock higher still but it was always more of a lottery as to whether you got a good batch on your modules.
There's an old but pretty comprehensive list of RAM dies and their performance here on reddit. They are mostly tested on 1st gen Ryzen on which the memory controller is pretty awful so you should see markedly better results with Zen 2/3.
As you say, dual rank modules can be harder to OC than single rank and this can be an issue on ITX motherboards where 2 DIMM slots are the norm so there's usually a trade off between OC potential, memory capacity and cost. For example, you're much more likely to be able to hit that 3600 MHz sweet spot with x2 8GB single rank sticks compared to x2 16GB dual rank sticks. The memory controller on Ryzen does seem to struggle with this although it appears to be increasingly alleviated with newer generations of CPU.
Unless you're loaded or have a very particular use case where by you need the fastest RAM available, my advice would be, don't go spending obscene amounts of money on RAM modules. Yes, 3600 or higher with 1:1 infinity fabric is the goal, however the gains past 3200 MHz are diminishing. Between 3466 and 3600 is negligible. If your build is for gaming, remember timings are just as important as frequency and you can certainly achieve better FPS by striking a balance between high frequency and tight timings. For example, a clock of 3466 @ CL16 is likely going to yield better performance than 3600 @ CL22.
Hopefully some of that is useful to you. Good luck!
