That makes no sense, the point of pressurising a G-suit is to physically press on the pilot's lower body and drive blood towards the upper body, think adaptive high-pressure compression stocking.
Pressurising the cabin can have no such effect.
Plus the point of G-suit is high-G manoeuvres, not linear acceleration or deceleration: untrained humans can handle 17g eyeballs in and 12g eyeballs out for several minutes versus instants of 4~6 g along other axis, Stapp's work demonstrated that properly restrained humans could walk away from 46G eyeballs out (decelerating while facing forwards)
For what purpose? A souped up train isn't going to do high-g manoeuvres.
> It may break your neck on sudden deceleration though.
The only deceleration for which that'd happen is an explosive one where you'd dismantle the carriage into a wall (and even then it's unlikely to break your neck), and a broken neck would be the least of your worries.
Pressurising the cabin can have no such effect.
Plus the point of G-suit is high-G manoeuvres, not linear acceleration or deceleration: untrained humans can handle 17g eyeballs in and 12g eyeballs out for several minutes versus instants of 4~6 g along other axis, Stapp's work demonstrated that properly restrained humans could walk away from 46G eyeballs out (decelerating while facing forwards)