I can't help but feel that the scoring might be too random to actually give you a reliable number on the strength of your deck. At least if you have only one core set for construction (it's not enough to build reliable two-sphere decks, there just aren't enough cards).
Actually in general I feel that the encounter deck mechanism doesn't provide a very stable game experience. It's just too dependent on which cards you draw during staging, especially in the early game. I played the Journey down the Anduin scenario three times so far and two times I had really broken starts.
Once, I turned up a Marsh Adder in the set-up phase, added the Hill Troll and got me a Wolf Rider followed Chieftain Uthak in the first staging phase. Sure these enemies remain in the staging area for a while, but facing three of these bad boys in the first round makes questing and battle really difficult.
In general I feel the difficulty varies rather strongly according to what you draw of the encounter deck. Sometimes you don't even get victory points. Sometimes you get a really easy run and sometimes you're just overwhelmed no matter ow strong your decks.
I do love the game and think it's very fun, but I didn't expect the game experience to change so drastically from game to game.