First of all, I totally agree with you on the looks, they are damn sexy. But you’ll be limited in terms of chain ring size. Plus, if you get one with a built-in power meter, then power meter and chainring are one unit that have to be replaced together. I think you’d be better off with the regular crank. It tops out at 46 teeth, but honestly, that’s plenty in most situations.
You are right that this also depends on your self-selected cadence. At those speeds, mine is about 100 and I am usually in my 42:11. I can reach those speeds on the flats if the wind is right and/or I get a decent draft from traffic. In top gear, I’m at 54 km/h at 100 rpm.
Still, if you know you are usually in your 90s or so, you should be fine with a 46-tooth chainring. 90 rpm in your 46:10 translates to 53 km/h. And 46:50 is a really easy gear, much easier than any official road bike gearing, so you should be all set to venture in the alps!