^ agreed... 12' will be great for the 1st - 2nd season. But once you dial in the basics and start throwing different combinations with 2's on, your not left with much time on the rail to play around with different combinations.
Bottom line is it will be hella fun and worth it, but later on most likely you'll want something longer / different, and that's cool you can always add to the rail or modify your drop-in to be taller.