Sam, you do realize that daggerboards aren't in a fix position right? You can pull them up to a desired height? Sorry to be a wise butt but your just about as bad as the Sunfish sailor when I was working at LaserPerformance who asked me to make him a short daggerboard!
Uwpwind with long boards, you're pulling the boards up around 10-12 knots, they don't get in the way and you'd have to seriously screw up to get thrown forwards into your daggerboard upwind.
Downwind, in light air you're leaving them mostly down or pulling them up (very condition dependent) but even so, this doesn't change from the old boards.
Downwind in breeze you're pulling up your boards and if you stuff and you're not trapping you're might end up flying into the board, but this is fairly rare and again no different than if you have short boards.
Think you'll be okay?