I started with discs on my mountain bike, then I added drum brakes to my commuter bike, now I'm hooked on getting rid of rim brakes. I just built up my new gravel grinder with mech disc and it's sooooo much better. My road bike is built with 0% carbon fiber, 9 speed cassette, triple crankset, steel frame from 1978 (full 531!). When I can buy a nice carbon fiber road bike with disc and Di2 for less than $2k (and take 28mm tyres) I'll have a new road bike. Being Retro-Grouch is well and good but not at the expense of moving forward.