I just ordered the 10 as well most people say the 20 is easier cause you dont need to work as hard if you're not trying to get the full amount of speed. I dont care though I got it for this year and plan on selling it cause I dont think I'll be hitting much urban next year when I'm in the military.
with expirience 10 foot wont get you enough speed to hit any largeish kickers we ended up having to tow in on a minivan cuz the bungee wasnt fast enough all we could do was small rail hits so yes get a 20 foot
its plenty of speed for getting onto a rail but if you want to get creative and hit different types of features other than standrd down features then the 20 is well worth the money