Yes. When I'm ready, I'll most probably do full suspension.
Regarding your first question, I don't think it is agonising if done right. If you search for it, there are info about how to do it, it's not that difficult.
I have tried it a couple of times where I tried to push a belt against my neck with my arms pointing backwards behind my head, and pulling the belt that way. No knot or anything, so if I lose consciousness, my arms drop, and nothing happens.
For some people it's easier to pass out, for some it's more difficult. I couldn't do it. I guess it depends on your anatomy, how your neck is built, how muscular you are, how big your Adam's apple is, how deep your arteries are etc.
Then I tried to put some padding on the two sides of my Adam's apple, around the area where the arteries should be. Like a pair of socks folded into a ball, and put one on each side, put the belt over that, and pull. Big success. Took about 10 seconds until I blacked out. I imagine if I did full suspension this way, it'd take about 10-15 seconds max, and I'm gone. Like ease into it, then after 5-10 seconds kick the chair under me, and that's it. I wouldn't feel anything. So that's my discovery.