So, I've got the M200 in mail today.
Quick notes.
The fit, while overall good, has serious seal issues with the stock tips. There have been many suggestion for replacement tips. I, having owned 10+ iems in the past year, went through all my iem tip collection, and tried about 10+ pairs of different kind of tips, varying from normal silicon sleeves, dual flange, and even foams. Only few of them fit, but I found the perfect one. It seems like foam is the best solution for M200 as the seal is the issue here.
Here's my recommendations. My favorite iem tips are shure olives. Small ones. Of course, they don't normally fit the M200. M200 have huge tips. So, just remove the cores of the olives, and use them. They're on my M200, and manages to get the job that with supreme comfort and not much change in overall SQ.