Yes, the tension is usually higher on the side with the fixed cable, as this has to flex the outer cable running to the other arm in order to pull away from the rim. The pads are going to be closer to the rim than on a normal brake (as leverage is increased), so the wheel needs to be true - I've also got a brake booster on one to reduce flex and firm up the brake feel.
They are tricky to setup at first but get easy with practice. Also, I've found they're best with normal brake levers, no SLR or dia-compe power cams as that just results in spongy feeling brakes.