Max speed w/ 4 DIMM being lower does not mean that you can’t run 4 supported sticks at their advertised speed, it just means that the fastest sticks are not supported in sets of 4. As long as you stick within the supported specs, you should expect to be fine.

I have 6 rigs in the house running now using AMD 3000-5000 series CPUs, every one of them has 4 sticks of RAM at advertised clocks, and while I’ve had stability issues with certain BIOS version / chipset / CPU / RAM stick combinations, I’ve never found that 2 sticks ran more stable than 4.