None whatever. It's working great. I've adjusted it a few times and it adjusts the flow smoothly. Night and day different than the quarter turn valves that I've tried.
I was really surprised that it will adjust as low as it does considering it's on the suction side of the pump. I think I could get it down to 1oz/hr if I tried a little. You really need a calibration chamber if you want to get it that low. It'd be easy to make one if you needed to.
I still haven't heard from the other valve but I suspect that it'll just show up one day without warning.