Is SI or SE better for Corsairs?

Seconded^. If your gun speed isn't at it's max, SI would be, I assume..? But if it is, SE is definitely better. I tried SI with my NL (using Craven), I felt a small difference, but it wasn't very noticeable. Corsairs on the other hand, I'm sure SE doesn't affect them as much as a Night Lord, so SI would be better for the slower guns.

Actually, SI doesn't work for NLs. It makes a huge difference for Corsairs and other classes that it works on (Buccs, Warriors, Bowmen w/ Strafe, CB, etc).

I'm not yet a Corsair. However, I know that I will be using a Concerto, which wields a "fast" speed.