After spending a month of research I finally jumped on the power meter bandwagon. As a data junkie I wanted a power meter that is reliable and could generate numbers (along with my Garmin head unit and HRM). Calibrating takes a couple seconds. The payoff comes when I return home and can do a quick peruse of the ride summary. I know it is a long term disposable spider design but as long as I stay on top of the chain wear it will give me years of service with just batteries to replace. If you are looking to build a project bike and have bought into the SRAM universe this is a no-brainer.
When I was younger, I wanted the lightest titanium everything. Now, I want more teeth (on my cassettes) and longer cassette life. Campy gear lasts a long time. After 13 years, my 10 speed rear derailleur snapped in half (I think it was a chain issue), so I had to upgrade to 11 speed. I believe the 11 speed system performs better that the old 10 speed.
Getting back to cassettes, over the 13 years of my 10 speed system on two bikes, the Chorus cassettes showed less wear than the titanium. With care and cleaning, I believe the Chorus cassettes will give you many years of service.
I got a set of climbing specific wheels and wanted a cassette that would leverage that even further. The 32-11 was a good call. I really don't use the 32 that often (most climbs are fine with the 30) but when you hit a wall and need just a little more leverage and a little more confidence, the 32 is nice to have. I was worried about chain length because my other wheelset has a 30-11, but I have had no problem. If I was moving from a 28 to a 32, I'd probably need an extra link or two, but the 30-32 switch has performed fine on an Ultergra Di2 longcage derailleur.
I recently had to replace my rotors. The original equipment was Ultegra, but I always thought that the black interiors of the DA's were jsut cooler looking. According to the literature, they are slightly lighting and the black brake fins disperse heat better. That may be the case, but I can't say that I really saw a performance difference. But the DA upgrade was only a few bucks more, and they do really improve the look in my opinion. Usually, I would opt for performance over looks or cost, but in this case I'll probably always stick with the DA's.