I got my P (175) and S-Line (177) MD2s the other day. Mostly been playing around with the P-Line (R-Pro) and it's a very good disc. Can handle all the power I can dish out (with a good release at least), turns a bit and then locks on, a bit of fade at the end. Pretty fast and has good glide, flies far if ripped. All-around reminds me of the X-Buzzz, except... Better, somehow. I need to do more testing. So far I'm loving it. The plastic doesn't seem as feeble as the driver R-Pro I've seen, but not as durable as putter R-Pro either. The grip is phenomenal though, I need to beat it some more to find out the durability.
I only threw the S-Line a few times, and wasn't really dialed in that night. It did seem to fly a bit different from the P-Line though, bit more of an S-flight. I definitely need to try this out more.