The shorter the run, the better. 125 to 200 feet is fine with good quality quad shielded RG-6 coax with solid copper core. A run over 250 feet might benefit from a quality amplifier, but it will degrade the satellite signal. The longer the run, the more switch and motor control problems. Do not go cheap on the coax cable if you are installing a long run. Might even consider RG-11 solid copper core for runs over 250'.
The prime focus design has no offset angle, but that makes no difference when performing a site check. Both a prime focus and an offset design look at the same point in the sky and the reflector must be fully illuminated by the satellite signal. The app does not care what the reflector type is. It only shows you wher the satellite is positioned in the sky.
