If its on the QVL its tested to be compatible. It's that simple, anything else is at your own risk. Plain and simple.
I'm looking to upgrade my RAM to 32 GBs. I currently use the MAXIMUS X HERO. I know that 2x16 is better for the memory controller than 4x8GB but would there be any issue if I choose to go for a 4x8GB setup? The ram will remain at dual channel as far as I know. It's easier for me to go 2x8 now and in a month or two for one more 2x8 kit instead of going straight to 2x16, plus the aesthetics are a factor that I consider. I'm going to run it on the XMP Profile and nothing more.
I would be glad to hear your thoughts/opinions on the matter
I'm about to add this kit: CMW16GX4M2C3200C16 / CMW32GX4M2C3200C16
According to Corsair it's compatible with MAXIMUS X HERO, is that true?
In that case just go for 16gb, more than enough for the needs you've specified. As to the kits themselves, both are excellent it's really down to the aesthetics your after, as that seems important to you, so just go with whichever you feel suits your build.