As a past 501st-er, sweating is just part of the gig, but 501st armor is usually ABS or HIPS so it's lighter and can 'breath' better than foam. Yep I'd imagine it would get pretty steamy in that for hours on end.
This one is a really sharp build and the foam thickness doesn't really stand out as much as I thought it would. The problem with these is sometimes the painted foam never matches the colour of the helmets, but you get that sometimes even with HIPS and ABS armor.
Most HIPS and ABS armor is in the $800 - $1500 price range so using foam is a super cheap alternative. Really great build.