DrJon’s done this already: Linky. He got his down to 165gms, about 10 grams heavier than the Race pedal with a fair amount more platform.
A long time ago, it was a fairly common hack to file large chunks off the original ‘grenade’ SPDs – this was in the early to mid 90s. It always looked like a fair old faff, and back then (as now) I didn’t have the extra dosh to drop on a brand new pair of pedals just like that.
I’ve owned XTR pedals that have failed in the manner Njee describes, and Shimano’s importer gave my local shop a credit for the cost, as far as I can tell without question. They might think again if the pedals had been chopped around.
I suppose the question I’d want to ask is whether you are happy with all of the above before you go and chop up some very expensive pedals. If you are, go for it.