My pal Don just got his Foil Premium frame. He built it up with Sram Red 10 speed and Zipp tubulars. Thusly equipped, his bike weighs 14 lbs., 4 oz.. that's even lighter than I anticipated. My bike, (same frame but with D.A. 9000, Di2 10 speed, Williams 38 carbon clinchers with a G3 Powertap) with Di2, clinchers, power meter, is 16 lbs, 2 oz. The Foil Premium is a very light frame, Scott claims 840 for the frame, 330 for the fork. Even if it's 900 grams or so that's lighter than any other aero frame out there, and lighter than 95% of current high end frames across the board (few frames today are 900 grams or less). Loving this bike. I suppose it's stiff compared to the S2, but that's mostly good, climbs better, it's a balls out race bike with no compromises, and carbon fiber is comfortable enough regardless. I loved the S2, but this bike seems closer to the Addict, which I also love, but it's more aeroer. And it is by far the coolest looking bike I've ever seen, the stealth gray finish and internal cable and wire routing. Very slick indeed. Very impressed with the Scott product line in general.
Bear in mind that frame stiffness is supposedly about one third of bike comfort. The other two thirds are factors like tire pressure, wheels, handlebars, seatpost, seat, etc. I have carbon wheels, handlebars, seatpost, Toupe saddle with a very flexible shell and ti rails. I've only ridden this bike for 3.5 hours at a stretch, but I had no comfort issues for a ride of that length.