from my experience, 4GB of RAM will improve the speed at which apps load and generally the whole OS will seem faster. lowering the 1066 to 800Mhz wont make that much of a difference.. it could knock a few fps off but nothing serious.
Why did u take 2GB 1066 out, overclocking issue?
Ryzen 5 5600, ASUS ROG STRIX B550-F GAMING WIFI II, Corsair Vengeance RGB RT 32GB 3600MHz C16, MSI RTX 5070 Ti Ventus 3X OC , Corsair RMx Series RM750x. AOC AGON AG324UX - 4K 144Hz 1ms