You don't save much. {} still requires a modifier key. You get [] for "free".
There is a whole usability universe between shift and AltGr, the former being accesible with the other hand.
I always changed to ANSI layout, independent of the layout of the actual keys. Now I carry a HHKB with me, and connect through BT to whatever computer I want to work on. No matter what human language I write in (I do some) I prefer using accidents like tildes and umlauts with modifier keys.