Almost all my Co2 pistol fiddling has concentrated on souping them up for greater power, but your 59 consistent shots at 500+ FPS is way better than I would have imagined. Good job.
Like Scot, I'd be curious how an even lighter striker would behave, but I doubt it would do any better. I agree with him that it could be more prone to valve-lock issues in higher temps. I've had 2 Pardini K60's and an FWB Mini 2 that were sadly inconsistent in temps as low as 80 degrees; sometimes to the point of utter uselessness. I suspect light strikers at least partly to blame.