Or ultimatly you could just follow the pickup trend and offer only two sizes; Gibson (ish) spacing/raduis and a Fender (ish) spacing/radius, if there is no loss between the poles then I can see it matters.

I 've just looked at a few of my guitars and there dosnt seem to be a difference in pole spacing from bridge to neck pickup so its not an exact science anyway (I think they are only sold as neck or bridge based on the resistance/power output)