I used a birth stool of this style - deBy birth stool
and I'll certainly say a toilet seat would have been more comfortable, should my bathroom have been so accommodating, hehe. It bit sharply into my legs. It wasn't really so much for.. sitting on I guess. A narrow rim and low on the padding sorta discourages lounging long, heh. But - that kept a lot of weight on my feet and I certainly wasn't on my tailbone. I noticed this less as things went along. I actually used it much like those pictures with the birth sol chair during many contractions come to think of it. There certainly were more comfortable places to be maybe, but after 30 hours it was too extraneously tiring to stay standing, squat or even keep getting up and down - and I think baby girl was needing some verticleness to help her position. That all said, I'm really glad I had that birth stool - I think it worked great for me and I'm wondering how the heck to have one available for my next birth.
*edited to add that I checked my birth pictures, but none I've online even approach decent
My legs were spread about as the woman's in the link above are though most often, but sometimes falling apart wider.