A few thoughts:
The faster you go, the more pressure you have in the canopy, and the more resistant it is to collapse. At the same time, the faster you go, the worse the turbulence you experience. (Which is why aircraft slow down in severe turbulence.)
In general I think letting it fly is the best option in all but the worst turbulence. In bad turbulence (i.e. the canopy is seeing minor collapses and it's hard to keep it flying straight) partial brakes puts you in the best position to reinflate if you do get a major collapse. This is especially important near the ground, where you have very little time to reinflate if needed.