The 90 I've had for over ten years and I've never had a problem with it. It must've fired twenty thousand or more shots and it's not missed a beat. It's my main gun and gets a fair bit of use.
The Xocet was done about a year ago and probably only done a thousand or so shots. but so far so good.
The other two have only been done a couple of months and haven't had much use yet, only a few hundred shots each, so dunno. They're kind of spares and I do collect springers!
One thing though, if the 90 ever does leak, you can top them up. All the after-market kits, you can't.... They are se