Agreed. I have a seat harness (well it's a waist harness with a small seat...flying objects) for over powered big boost f*** off or go home sessions...you know the ones where the kite drags your sorry ass down to the water whether you like it or not, then a waist for surfing and freestyle (which is getting proportionally softer with age.... ).
But most the guys I kite with just use a waist.
But when I'm locked and loaded I like the extra support.
But honestly if the seat works for ya, get a sliding spreader and be done with it.
To consider moving to waist harness has some progressive quality to it is as stupid as the strapless surfboard riders banging on about how this is the technical pinnacle of our sport.
Anyone whose surfed for many years like me must find this slightly amusing.
I used to use a seat with sliding spreader but I like simplicity and in the end just got a waist that I don't put on to tight so it moves around a bit...when riding strapless of course on a SB.
Oh the best waist with with a sliding spreader is the one that fits best...try some.