Before this turns into a pros and cons of uppy downy seatposts thread….
The Joplin3 is on sale at CRC just now for £110. I hear that the distributors will warranty it if there's any issues (as I've heard a couple of people have problems with the J3) and even in some cases replace it with a J4.
I've bought one on that principle to give it a shot.
now… as for the discussion… I used to have a GD on an old bike and loved it.
I like to ride fast, both up and down. Yes, everything can be ridden with the saddle up, but some steep techy stuff or sections of trail with jumps in, can get you into real trouble with the saddle at full height – I came off last saturday on a really steep rocky bit coz I couldn't be bothered stopping to drop my saddle for a tiny section… more to the point, I couldn't be bothered with the faff of setting the height again afterwards.
Basically, to ride everything fast and smoothly, I need the saddle at full height for the climbs and dropped a couple of inches for techy descending.
I'm more than happy to be sociable and stop and chat, but sometimes I just wanna keep riding.
The big thing though is I hate my saddle at the wrong height or not straight and can't be doing with the faff of getting it right after a dropped saddle section.
Height adjustable seatposts mean my saddle is always at the correct height, up or down, and always straight. No faff… more time to ride, more time to chat, less time getting annoyed with saddles at the wrong height.
Other folk's mileage may vary. No-one says everyone should have one, but for some, me included, they improve my riding enjoyment.
Nuff said.