There’s a middle ground between the coresaver and pressure suit, 661 do their assault suit which is torso and shoulders but not forearms, works really well as it’s easier to get a good fit when you’re choosing your own arm guards. Also obviously easier to dispense with one piece or the other. (other companies are available 😉
I use an IXS Hammer but it’s hard to recommend, the protection and comfort is good but the back protector is massive and turns you into a hunchback)
Actually now I think of it I still have an old Assault Suit somewhere- had to replace it for race regs but it’s still good, if you want a cheap option.
Armour can’t stop a broken collar bone or vertebrae unless the break is from directly landing on a rock etc. Which isn’t often how these breaks happen.
It can spread the loads a little for collarbones but yep, chances are if you were going to break it, you still will. You do slide and roll much better in armour which is the main difference (also depending on the rider might be less likely to stick out an arm)
For vertebrae… spines are pretty easy to protect from impact (which is a likely result of a big crash) and from overextension/twisting (also likely). What’s not so easy is c-spine injuries, that’s where toilet seats come in. So a body suit isn’t a cure-all but it could make a major difference.