Highly recommend 2x4GB for a number of reasons:
1. Less stress on the IMC
2. Equating to higher CPU, CPU/NB, and memory overclocking potential (with less voltage)
3. Easier to troubleshoot memory problems
You can for the most part offset lower timings with 1600 modules by going to 1866+ modules with CL9 timings.
Ive been testing 2x4GB G.Skill 2133 CL9 for two weeks now, my Thuban can run 2100MHz stable, but only with some special tweaking.
Intel i9 10850K@ 5.3GHz
ASUS ROG Strix Z490-E
Corsair H115i Pro XT
G.Skill TridentZ@ 3600MHz CL14 2x16GB
EVGA RTX 3090 Ti FWT3 Ultra
OS: WD Black SN850 1TB NVMe M.2
Storage: WD Blue SN550 2TB NVMe M.2
EVGA SuperNova 1200 P2
ASUS ROG Strix Helios GX601