If looking for improved vision for the rider, as opposed to making the bike more visible to oncoming traffic, I'd suggest mounting your aux lights higher and not on the calipers. If you aim the Moto light types properly (angled slightly down), you aren't going to get as much spread and fill as you would with lights mounted up near the turn signals. And if you aim the Moto lights improperly (angled upward), like many seem to do, all you will be doing is blinding oncoming folks as those bouncing beams hit them right in the eye. I've gotten so I hate to see a bike with caliper mounted lights coming toward me, since most aren't aimed correctly and they bounce all over the place with the movement of the wheel.
JMHO - Jerry