Intel memory controllers are generally very good at using whatever you give them. Picking a random X99 motherboard manual indicates that this is still the case.The 5820k is still a bit of a mystery to me though when it comes to ram, does it need to have 4 sticks, are two fine to start, its hard to find definitive answers.
Personally I would only go with LGA1150 for either
ITX build or
tight budget therefore go with i5 or
crazy overclock aiming for 4.6+GHz 24/7 or
upgrade mobo/CPU every year
For anything else I don't see the reason to go with 4790k instead of 5820k. 12 thread 28-PCIE vs 8 thread 16-PCIE will make a difference in photo/video editing and future gaming. If you happen to do lots of heavy multi-tasking, 5820K will handles that much better and runs cooler. As for motherboard, even X99 sli plus has m2, NVMe support, and decent VRM. For a little more, you can get the better ASUS board. I personally think $250 X99 mobo just worth a lot more than a $250 Z97 mobo.