Well, being the long-time Spit guy that I am here's the (partial) lowdown:
In terms of turn rate (best to worse): Spit I, Spit V, Spit IX, Seafire, Spit VIII, Spit XVI, Spit XIV
In terms of speed (fastest to slowest): Spit XIV, Spit XVI, Spit VIII, Spit IX, Seafire, Spit V, Spit I
The I has 8x.303's. The XIV and XVI have 2x20's and 2x50's. The others all have 2x20's and 4x.303's.
The XVI rolls the best but it is the worst stall-fighter as it's not as stable as the others, but once you get used to where the instability is it's just fine. The XIV is also bad but it wasn't designed for stall-fighting.
Every one of them is a fine ride in the LW MA's, including the lowly, oft-forgotten Spit I.