For racing, a loose rig would allow the mast to lean / rake more forward for better downwind performance and lean / rake aft for upwind performance.
The rule of thumb I used was to get the rig aft where the main blocks would nearly tough when fully sheeted. The shrouds were loose enough to grab one shroud and rotate your hand 90 degrees.
Agree though... keep it more snug for fun sailing.
Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA