Did C2S last year, want to do it again this year... just coming back from a injury though, think I upped my training/distance too quickly.
Used to do 30-50km a week, but i'm starting off easy again.
It's an awesome feeling
edit: I use all the gadgets.. heart rate monitor, GPS, cadence foot pod.. I just love the stats, loading them into the software and using it to compare runs and how i'm progressing.