I just bought a 2015 Synapse Carbon Ultegra Disc DI2 a couple of months ago. I love DI2. My previous bike was (is) a 2010 Roubaix wi SRAM Red. I did an extended road test on a Synapse with Rival to get the feel for the frame. The DI2 bike is heavier partly due to the wheels, Mavic Aksium discs. I fixed that by getting some November wheels that are 350 grams lighter. I used rim brakes for my first 150,000 miles of riding and never had too much trouble. But I gotta say, I like discs! The lever action is light, and modulation is nice. The wheels do use QRs, but I assume the adapters to convert from through to QR will be available for the foreseeable future. Anyway, as others have said, test ride some bikes, and pick the one that feels best to you. Even if it's that archaic steel stuff.