I don't know whether this is better than a hub dynamo or not. Both will introduce resistance to turning the wheel because of the interplay between the magnets and coils. Since the magnets/coils are more to the outside of the rim with this system than with a hub unit, it would seem to not need as heavy of a magnet nor as many windings in the coil, since this placement moves the magnet past the coils faster and thus generates more electricity for a given size magnet/coil.
As far as the resistance to turning though, I'd expect that to be the same for both systems.
That said, I'm speculating about just one characteristic of the system. The only way to know for sure is for somebody to compare this to a hub dynamo and publish results.
Edit: My comment about needing smaller magnets may not be accurate since the magnets/coils are mounted to the fork/spokes and presumably have a lot more space between them when designed as integral members of the hub.
Last edited by Walter S; 05-06-14 at 10:10 AM.
Reason: another thought