I really found both the SL and the Heritage to be more user friendly than other boards out there on the market. They really felt to me like point and shoot. Neither one of these boards are overly fast, you can flat base on them better than most in their comp set, edge hold is solid, and both are forgiving in the sense that if you lose balance or get your weight out in the wrong direction, they aren't going to jar you with a nasty fall.
Personally, I'd go with the one with the long term potential. The Heritage is definitely stiffer.
You are from Colorado? Go to Vail and see the guys at One Track Mind. They have both the SL and Heritage in a few different lengths, and they charge like 40 bucks for the day, and you can trade in and out as much as you want.
Unlike some of the others here, you aren't going to notice that much of a difference between the two, besides the stiffness, and possibly turn initiation. In my opinion, and this might have just been my experience, but both the SL and Heritage were more forgiving than many other brands. K2 has some easy stuff to learn on as well.