stiffer front ARB alone will increase understeer and make the car corner flatter. stiffer rear ARB will decrease understeer and make the car corner flatter. both together you won't change the handling characteristics, but it will corner flatter hence giving you an advantage.
HOWEVER the Golf's main problem is with understeer, so a rear ARB on it's own is a better value-for-money mod as it will improve the handling better than fitting a front ARB on it's own, and as you said it doesn't require you to drop the front subframe to fit/take off come sale time.
i'm only going to get a rear ARB and WALK. haven't decided what ARB yet.
