Excellent! You’ve picked up on an inside secret of electrical and electronics engineers… that you can’t believe the hype of some marketers when it comes to wiring. Back when I was in the home theater installation biz, brands like Monster Cable sold wiring for 10 times the unit price of generic wiring of the same gauge with false promises of extracting better sound. Hogwash!

Good for you for showing that you don’t need the expensive Schmidt wire. It’s high quality but not worth even one quarter of the price.

I used a similar co-axial signal wire (sourced from a local electronics supply house for $0.25/foot in bulk) when doing the custom wiring for two recent Weigle builds:

http://www.flickr.com/photos/7516215@N03/8699466807/

http://www.flickr.com/photos/7516215@N03/8482624873/

The only thing I would warn about is that the coaxial wire (carrying taillight hot) should be no thinner than 24AWG, otherwise you will experience some voltage drop across the long distance between the dynamo output and the taillight. Maybe not much, but still not a good idea.

The downside of coaxial wiring (or any two-conductor wiring) is that you can’t run it inside the rolled edge of a Honjo Fender. Only narrow single-conductor wire will fit there, using the fender and frame as common ground:

http://www.flickr.com/photos/7516215@N03/8696651637/

However, the 3mm coaxial cable can be routed along the underside of a fender through little aluminum guides glued in place:

http://www.flickr.com/photos/7516215@N03/9491830768/

And when you REALLY want to get fancy with slick 3mm round wiring, you can get a 3-conductor variant to incorporate both headlight and taillight wiring into one cable system. Here I’ve replaced the four thick wires (2 are shared ground) of an IQ Cyo with a single 3-conductor 3mm round cable:

http://www.flickr.com/photos/7516215@N03/8733545658/