Today for overclock testing purposes I removed 16 of my 32GB ram and after I had finished tuning I decided to give MSFS a go. Not flying airliners but at KLAX, TAA100, full ultra, LOD 400 and default traffic @ 1440p I never saw more than a frame or two difference and only the slightest of loading in stutters (even this could possibly be attributed to me no longer having a ramdisk cache). Detail and texturewise there was zero difference.
Make of that what you will but I say the faster your ram (latency) then the less of it you actually need.