The Cseries is about 108(CS100) to 160 seats on the proposed CS500 in dual class. I don't see Delta buying any CS100's, my guess would be 75 CS300's with options for 50 CS500 when they become available, and some 737s. That would replace the MD's. From last time I was in Montreal, the C-Series looked to be about the easiest airplane to fly ever.