I purchased a new Defy 1 last August. I'm almost exactly your size. The dealer was closing out the 2015s and only had a M/L in stock. I rode it around the parking lot and decided to buy it, the price was too good to pass up.
I sold it a couple of months ago. I just never felt comfortable on it. The height was fine but the reach was too long for me.
Ride both sizes back to back, and not just a short spin around the parking lot.