Really – are we still throwing bile at Kashima? How very 2010 of us.
Anyway as others have said piggy-backs are there for more oil volume (like ‘metric’ shocks). Which not only helps on really long descents when it could get hot (think massive Alpine descents not just 4 min runs at BPW for your average muggle rider). But the extra volume also allows for more control and more consistent damping even without heat issues.
It’s hardly night and day though and for riders who simply set rebound and compression (if they have it) in the middle of the dial because that’s probably average then it would be utterly wasted it’s so subtle.
I was always a the guy who left things in the middle because I’m terrible at ‘feel’ I just ride as fast as I can/want, I don’t perceive suspension well, but when I spend the time to get it dialed in I just go faster without trying, more than just speed it gives more flow on trials as there a lot less ‘boring bits’ as you’re carrying more speed.
Remember rebound isn’t about ‘average’ it’s about controlling the shock pressure / Spring, if you’re bob on 12.5 stone and run 20% the middle might be right – but probably not, if you’re anything out of the average it’s probably just wrong.