Nedstar, for the record, the lighter one will be very roughly 1-2% faster that the base model.
As a very rough rule of thumb, speed on a 12'6 is roughly 85% Engine, 10% Board, 4% paddle, and 1% fin.
So how do you rate your engine out of 85%(?)... Most 12'6ers these days will score 8-10 out of 10. Good paddles will score 3-4 out of 4, and a decent fin like the one in the 404 is the 1%...
You can buy 15% of the equation....

We're all born with 40% to 60%, and the gap is fitness, hard work, and reading the ocean...
(very rough rule of thumb anyway... Maybe you can say 75-20-4.5-0.5... in that sort of range anyway..)...
PS - this is not meant to be negative in any way!