When I paired my power meter to the 520, I was able to set the crank length. I believe it asked right away to set it, and you can change it afterward by going into the sensor details.
The same applies with wheel circumference when it pairs to a speed or speed/cadence sensor.
Hope this helps.
I've done two rides with the 520 (after coming from the 500 as well), and I'm very happy with the unit. Couple minor wishes (would like to have beeps for start/stop/auto pause and alerts, but not keypresses, etc. Unlike the 500 it's all or nothing, hopefully this will be fixed in a fw update...) but overall I think it's a great unit, especially coming from the 500.
gm
That's only for Vector, not for 3rd party units yet. There wasn't a date specified on when the 520 will get the update, only that it will. I'll press again for a timeframe this week at Interbike.