If you're going to put peeps on it or leave on the irons then the Trainer is a better rifle and in the long haul I think you will want one. The disadvantage with the youth stock is that with the longer barrel the balance is going to be off. If you think you'll only shoot with a scope then the extra sight radius won't matter, so you could get the Scout and get a full length stock later. But if you have the funds then get both. I have a scope on my Scout with a full length stock that I use for silhouette. On the other I have BRNO peeps.
BTW, if you haven't already, check out Appleseed (appleseedinfo.org).