No you should not need to upgrade. The pro reg has an adjustable collar for the full nipple other than that same adjustable reg.
The standard and ultralite regulators, we use a coil spring inside which (brand new, out of the box ...and as long as the marker is functioning properly) will net you a fluctuation in velocity from about 5-7 fps.
The PRO regulators (Adjustable, SLP, and SHP) all come with a belleville spring stack, which we found to be slightly more consistent than the coil spring design. With a PRO reg (brand new, out of the box and as long as your marker if functioning properly), you should see about a 3-5 fps difference in readings, shot after shot.
Tonycon is right though. One of the main features on the pro that is not available on the Standard or Ultralite is the rotational collar: