Some clarifying stuff....
Stratification.... When you are talking NWSG - you cannot put Switch & the rest in the same category... BB, Indian, etc. FLUFFIES (BIG BLUE, INDIAN) or normal looking grain types (western wheat, Virginia wildrye, etc, etc) - No - all those do not have the hard seed coat that requires stratification. Switchgrass uniquely does. You can get varying degrees of germination on switch planted without stratification. depends on soil type/moisture, rain, weather, etc, etc. You cannot beat the germination of stratified switchgrass though. I've seen almost no switch germinate that was late planted. I've seen some settings where almost all luckily did. And everything in between. BUT - yes, switch is the unique seed you want to stratify.
With above.... Drilling into weeds later..... If you're planning on mowing it all year, fine. obviously kill the heck out of weeds before drilling. Side note, again, UNIQUE to switchgrass.... Atrazine is the herbicide used on bare soil that often allows for no mowing to be needed if done PROPERLY. This is for Switch and can be used with Big Blue as well. Indian & BB are Plateau/Journey/Panoramic tolerant, switch is not (can take 2 oz roughly MAX). Indian does not tolerate Atrazine. Plateau does well on controlling weeds on ground with a lot of residue & junk on top, Atrazine does not. If you're mowing and not using a residual, all irrelevent
Just figured I'd confuse you all some more by throwing out a few more things all at once I know guys will wonder about.