I've got a roc-n-soc with air lift and back rest that breaks down to 3 pieces. Went through the quik-lok and others. They are not cheap but it ended up to be one of those things I should have bought in the first place. With my past back surgeries, It is worth it. Everybody I know who has one loves it.

I got mine about 20 years ago at office depot. It looks like one posted at Sound Seat, except it was less than a hundred dollars. It doesn't fold up but is adjustable in height. Not that portable but it has wheels so I can use it for a dolly if needed. It is designed for office and is called a drafting stool I think, I have 3 of them. Why is another story.
DonM

Sparky interesting choices here...

http://rocnsoc.com/new/

Whatever you get, get quality! Had serious base of spine issues until I started using a decent drum throne rather than a "this looks Ok and its cheap" model. It's a Mapex "tractor" style seat similar to this: http://www.online.angliadrumcentre.co.uk...w-top-488-p.asp

I got it whilst attending a Tyros 2 launch show! Still as good as new although I'm a weekend rather than daily user.

John....I had this same seat made by TAMA

http://www.tamadrum.co.jp/product/hardware_data.php?id=36&year=2012&area=2

......but, be careful that front part of the saddle will make your delicate parts ache over time in the seat at a long gig ......that's why I sold it. & they are heavy and bulky to lug around & break down also, I'd opt for the same seat but the ROUND configuration on a daily basis if that's what you need..

Good point about the lump at the front, it's not so pronounced on my older model. Nevertheless having to keep your bits away from that part of the seat helps the posture and stops you slouching, which could well have been part of my problem!

Once you go roc-n-soc you never go back.....here's mine. Sometimes you can make out better by finding a cheaper base and adding the back rest later.

[url=http://www.ebay.com/itm/Roc-N-Soc-Nitro-Drum-Throne-Original-Seat-w-Backrest-/150858725080?pt=LH_DefaultDomain_0&hash=item231fe176d8][/url]

Kinda makes you wonder why ALL piano benches are.... benches!

Maybe for little 61 keyboards, you can sort of get away with swiveling around a bit if you find both hands at one end or the other, but for 76's at least, I have never found this all that comfortable.

Something you can slide down or up a few inches has pretty much always been the primary seat for organs and pianos (and organs only have a 61 usually), to allow you to not have to contort your body and wrists when playing at the extremes...

However... I came across this http://www.ergonomicpianobench.com/ which seems to have some merit. Probably not as an affordable gigging stool, but the approach seems to have merit. If you can get something that can be added to a conventional folding bench (a piece of high density foam or maybe something like this: http://www.wellbalancedpianist.com/bpseatingguide.htm ) you might find yourself sitting comfortably enough that you don't NEED back support..!