" Some question the usefulness of the economic models the CPB uses, which (like all economic models) have never successfully predicted what the economy will do several years down the road."
The problem with any sort of fact checking agency in regards to economics, while useful, is far from a magic crystal ball. Economics is a pretty vague sort of thing that straddles the line between between the humanities and hard science. As a former economics student, I can tell you I've met very brilliant people who have adamantly disagree with one another, yet both have excellent insights. It's tough to definitely say that x plan is better than y plan, because there are so many what if scenarios and assumptions to rely on. That being said, I find it's generally better to trust whoever has articulated their plan better. Simply the act of extrapolating out their assumptions means that while they may be wrong, we can look and see if they've taken into account the metrics that matter.