I am sailing a mistral one design. What is described above is great if you want to go upwind / downwind, but sometimes you don't want to do that. Sometimes you might just want to go out and freesail with others in more of a baffing mode.
The longboard is excellent for that as well, but one issue I sometimes have is that with such a relatively small fin it can be hard work to stay on a beam reach and maintain decent speed while staying upwind, and it's even worse if you want to try jibes at the end of each run which also loses you ground. In this situation I often push the mast to mid track, with the centreboard up, stand near the rail and hook in, and I find that in either planing or sub-planing conditions, you can get back upwind very quickly and smoothly without bothering with the centreboard.
I also use this method when it's gusting below and above planing conditions where constantly lowering and raising the centreboard can become a lot of work, [ especially on mine where it's a bit stiff ].
Having said that, coming from a planing only shortboard backround, railing a longboard in a good blow is a lot of fun and can be deceptively quick.