ho i see…
with MR816 steinberg really gone like CIA TOP SECRET underground strategy 
after lot of complains about daisy chained devices not having zero latency finally we got the bad news it won’t work that way.
and other ridiculous thing with MR line is it won’t change sample rate via Adat as slave to other MR via adat(and probably other adat master interfaces)! needs to be connected to FW just to change sample rate.that’s a Badddd workflow!
generally yamaha in my experience is problematic on Fixing stuff and updating firmwares,for example in keyboard department korg always had better support and software upgrades and improvements over yamaha keys even when the product is not that new and probably not so profitable,but thats customer support and trust 
about machines upgraded to win10 with MR816 and stutterings,in my experience after upgrading to win10 from win7 i had to redo some tweaks has i had in win7 to eliminate DPC spikes… maybe its one of the issues ?! worth to check