Soldato
One thing to consider with any chair you're not happy with is additional cushioning. I'm not large or disabled, but my desk chair has a 3" thick memory foam cushion on it which is supposed to be for wheelchair users... ie very long term use. It made a *huge* difference to how comfortable my chair is for long periods of worki... ok, gaming and staring vacuously into the internet. It's just a cheapish chair from Staples, but I went to a store to try their range (several years ago) and picked the one which suited me best. But even that didn't feel great after a while. The cushion was about £20, but worth every penny.
Worst that happens is you end up with a cushion you'll eventually find a use for elsewhere.
Worst that happens is you end up with a cushion you'll eventually find a use for elsewhere.