There are plenty of threads on this subject. It mainly relates to offering more tyre choice as you say but mostly it revolves around ridding yourself of that ridiculous safety bead and therefore being able to, more easily, repair/change a tube at the road side.
As for ground clearance = minimal
As for worth it = definitely if you are a trail rider and don't want to fight your rear wheel in 30C degree heat when you get a puncture. For those of us, like you, who ride where there is no tarmac / phone signal it's worth it.. However, it's directly proportionate to time you ride in the outback or where there is next to no recovery. It's not really an issue for tarmac types though.
As for high speed stability = Mmm? ..If it's unstable at 'speed', it will be down to poor tyre pressures/condition/bearings/loading.......blar blar
