All depends on the powder. For example Unique is primer insensitive. Only a few fps difference. On the other hand, 2400 is primer sensitive (example Ruger .45 Colt load -> CCI-300 1022, WLP 1123, CCI-350 1181) . Over 150fps difference in test I ran. Then some powders like H-110 and IMR 4227 require a magnum primer for good performance. So, it is all about the powder. Unless you are the 'bleeding' edge it usually doesn't matter. When you are, you back off and work back up with the new primer.
A clinger. When guns are outlawed, only outlaws will have guns. Single Action .45 Colt (Sometimes improperly referred to by its alias as the .45 'Long' Colt or .45LC). Don't leave home without it. Ok.... the .44Spec is growing on me ... but the .45 Colt is still king.