I'm sitting in a cheap Chinese Aeron knockoff at the moment and it's quite good to sit [I]on[/I]. Everything is supported comfortably and ergonomically. The problem I have with this is after a while I find myself slouching around in the chair and I'm getting increasingly uncomfortable and less focussed on what I'm doing. The problem that arises when you start to do this is tissue is being subjected to sheer forces which is not comfortable.
Just now thinking this through I remembered I've sat [I]in[/I] a chair that felt totally different, almost like being in zero gravity. That was a chair from a transmission control room, the operators there have to sit for long periods totally focussed, same as train drivers, pilots and drivers of racing cars. That chair was a Recaro 24H Chair. This chair hugs your body, you really cannot move around in it.
Down here the Recaro starts at $2990, extra for arm rests and leather. If you're doing serious hours editing it'll probably pay for itself pretty quickly. The only downside is I think it'd be very easy to fall asleep in one of these chairs.
A very timely topic as I am seriously considering getting a new chair - my current one is woeful over a length of time. I'm going to check out the Aeron next week. Yes, it's expensive, but Grazie's advice in his post really puts things into perspective. Who knows, I might even save a bit on my albeit infrequent osteo appointments.
Cheers