What about the slide that has been floating around seemingly from AMD saying 4000 MHz RAM will be the new sweet spot for the 5000 series? Assuming this is real would the 4000 kit be the better one to go with? I may buy both from Amazon and just return the kit I do not use. I think I am already past the diminishing returns point with my rig (5900X & 6900XT) so I am willing to pay more for a little more power.
I wouldn't trust a leaked slide, and I doubt there'd be a significant difference between 3600Mhz and 4000Mhz on Zen 3 (if at all) so if you're getting double the capacity with 3600Mhz sticks then I suggest you go that route instead, Zen 3 is going to be less sensitive to memory clocks and latency than Zen 2 was, but if you want to buy both to test them out and return one of them that's totally up to you.