Well, my cheap disc was closer to £500 than £900, so it seemed like decent value to me. As I’m based in India and only in the UK sporadically, it was much easier to buy new, albeit probably poorer quality, than 2nd hand, purely down to logistics. Were I UK based I would most likely have trawled the classifieds to get something with a good reputation.
I’m not really in a huge position of authority to comment on how fast it is, or have enough data to conclude if I’ve gained any more speed from it. It certainly isn’t as stiff as a Zipp as the sides can flex if squashed – the more expensive offerings have some sort of core filling, some of them honeycomb I think.
I already had the nice aerobars and Di2 😀
One other point, clearly you’ll lose your powertap with the disc – have you considered how you’ll replace that, as that could be a more expensive move than the disc! I certainly spent more on my Quarq than my disc 🙂
Cheers, Rich