Matt, I have a couple boxes of 124 gr. +P and a box 147 gr. +P ammunition, to test out the comp. I'll pick up a few more, before I head to the range, to make sure I have enough to ensure that I am comfortable with the accuracy, as well as the reliability of the function, before I am willing to trust my life to it.
I actually had a chance to run some standard pressure ammo through my 509, when I had the Henry Holster Compensator on it. It did seem to make a noticable, if not ideal improvement, over the rounds that I put through, prior to installing the compensator. The only issue I had was that the standard pressure ammunition did not cycle reliably. The 115 gr. produced stovepipes, almost every round. The 124 gr. ejected completely, but only rarely cycled well enough to load the next round. The 147 gr. actually functioned fairly well, but still occasionally failed to load the next round, and did not lock the slide on an empty magazine. I thought it was odd that I noticed better cycling, when using the heavier ammunition, as most of the reading that I have done, suggested that lighter weight rounds tended to function better in compensated pistols.