I’ve just fitted an old Vybe to my Cannondale Slate. It was lying around spare after arriving on a second-hand bike a while back. It’s used but seems tight so I assume it’s working as a new one should.
It seems to work well, I’ve fitted the harder elastomers and spring to give minimal movement on the road but I do feel it working when I go off-road and hit bumps. It does have a noticeable top-pout clunk which I can see being annoying in full offroad use with a softer setting but for me it’s fine.
Years ago I had a Thudbuster which was very very good. Initially it’s a little disconcerting that you move backwards on the bike when it compresses but I soon got used to it. The action is very smooth and for what is an elastomer sprung system I was surprised how effective it was.
I’m not sure what availability is like on these high end suspension seatposts now, last time I looked they seemed to be a dying component.