Do prop specifications make a large difference in prop performance?

To put it simply, yes.  Propeller specifications will modify the performance of your propeller, and in some cases the modification can be quite dramatic.  If you change the pitch, diameter, or cup size of any prop it will have a specific effect upon either the low-end acceleration or high-end speed and fuel economy of the boat or possibly both.  Typically it is difficult or sometimes impossible to equip a boat with a propeller that will provide both great low-end and high-end performance, since a gain in one typically means a compromise in the other.  Your best route is to select a propeller that will best fit the applications you are using it for; taking into account what sports you will participate in, engine size, average occupancy, ballast, elevation and any other factors that may affect the performance of the propeller.