Pinholecam - How much faster did you find the 451 wheels over the 406 wheels?

I have a Moulton TSR that doesn't get split that often so could stand the slight reduction in practicality. I have seen a 451 conversion on this forum so know it is possible. I prefer the manoeuvrability of the Moulton over my road bike when I am commuting but wouldn't mind a bit of extra speed.