Lol. Project Butter is part of the Jellybean framework. Only custom roms on older devices using hacked together drivers can have JB and no butter. As MIUI is either based on stock Roms or IS the stock Rom, it always will have native JB drivers for the JB versions.
when you said that we need to wait for Qualcomm JB drivers for the M1 S
it is for the Dual Core qualcomm only , we can use the drivers from the M2 quad core version
Miui China did tell that the JB rom will be available ?