No offense intended here, but I've never required anything faster than f5.6 on a wedding shoot.
I only use f2.8 or faster lenses on them, but I haven't required the extra speed yet.
So if your getting good results with your 80-320 it might just serve you well.
I should also point out that I haven't needed anything longer than 70mm
Although I always bring longer lenses along for the ride.
I could have used something wider than 24mm this last wedding as well, but didn't have a chance to snap anything on for the 5 or so shots.