>>/15497/
The benefits are very  minor (weather data for past rides is one, I forget what else). I'd consider it a donation and payment towards trying to maintain independence active development. If you can spare the cash, it's probably one of the most deserving places on the internet to spend it.
 >>/15500/
That's 17086 cm! I do live pretty close to it actually, so at least it's somewhat hilly/rolling around here, not pure flat.