Formula boards are a bit more technical to sail and require larger (longer/deeper) fins to perform well.
They will plane as early if not earlier than the US 147, but may not be as much fun as they are completely designed for upwind downwind racing.
The US 147 is a bit more slalom oriented....better for back and forth reaching.
Won't go upwind as well or as deep downwind, as the formula race board, but unless you are racing,
most sailors never need to go that high or that low, especially in marginal < 10 knot conditions.