In my experience they are pretty dodgy. They CAN be an ok solution BUT not for the price of a pair of shackles alone
Let me explain...
They "flop"
Plain and simple they are designed to drop allowing the wheel to stay on terrafirma. Sounds good however there is no downward pressure on the tyre like a spring provides so the tyre breaks traction really easily
I found many times I would have wheels hopping about, going bite - spin - bite - spin where rigs w/out flop shackles would crawl. Hope this makes sense
It's like pretend travel almost
Also found mine are unpredictable at times which is a bit hairy
When you would expect one to open it wouldn't allowing next to no articulation
This is probably the joint binding which some designs overcome (like superior engineering ones). This is not great where you need control and predictability.
Finally pinnable ones are good but having to pin them every time you want to drive a steep slope sucks
Also don't reckon they're crash hot on really off camber stuff
Mine are climax shackles btw
Have also had ummm 'special' old suzisport non pinnable ones
Damo has seen em
Some drop shackle packages like the complete superior packages overcome many of these problems to some extent and I reckon if people have to get them superior are the go. But the price of a complete package will buy you a full coil conversion at Overkill or other fine shops
And the shackle packages still have their drawbacks like slopes, legality, and the 'flop' effect
Don't expect to buy a 500 pair of shackles and stick em on and be done with it is all I spose
Unless you're the uber ramp queen
I guess the ramp queen bit is a big selling tool for em anyway
There are WAY better options around for the money
End spiel
Mick