The type of base and ring determine the elevation adjustment requirements for a long range shooting. Long range shots necessarily incur a lot of ballistic drop. Hunters generally limit shots on big game to ranges for which the bullet energy is at least 1,000 ft lbs (for mid-sized deer, for example). To reach a kinetic energy of 1,000 ft lbs, the bullet drop is no more than 30 moa for most long range calibers at altitudes as high as 7,000 ft. Bullet drops are greater at lower altitudes.
Long range competitive shooters are more concerned with minimizing wind deflection than lethality, and will sometimes shoot to – or even through – the sonic transition, which occurs at much higher bullet drop values.
Off-axis optical aberrations and veiling glare become worse as elevation adjustment increases. For most scopes, these effects are not generally noticeable until the scope elevation adjustment from the optical center exceeds about 30 MOA. The use of >60 MOA adjustment scopes at their limit of adjustment will noticeably degrade optical performance. Proper selection and mounting of biased bases (i.e., 20 MOA bases) or use of Burris Signature™ rings will allow scopes with 50 MOA of adjustment to be used for long range hunting.
Proper boresighting of the scope to the rifle bore will insure that the shooter gets the maximum range from a scope with a given internal elevation adjustment. Use of biased bases is essential for long range hunters and shooters. Even if your scope has >60 MOA of adjustment, better optical performance will result if the internal adjustment is kept within 30 MOA of the optical center.
Turret knobs are a hot topic for long range and tactical shooters. MOA vs mil, MOA per revolution, zero stop, tactile feel, etc., are features that many shooter feel strongly about. Being rigid in this area will definitely limit your options. For many shooters, these issues are a matter of training. That is, with training, one can adapt to non-optimum adjustment features.