reports vary. but generally with full suspension you're gonna feel some pain, to what degree is just chance. i mean, your full bodyweight will be pulling up on your neck while tightening a noose around it. that's not gonna feel like nothing. some people say it's a 10/10 pain and their necks were sore for up to a month, others it was only a minor pain (as you've noticed yourself, the reports do vary). but generally you don't hear much back from people who do full suspension since it's extremely effective, so we don't have as many reports with full as we do with partial.
you'll make noise if you're near something, as the convulsions will have you bang against whatever is near you. you also may make choking noises, but only for the first few minutes.