What climate/location? Does your ground stay frozen or go through freeze/thaw cycles? For a gravel drive in a freeze/thaw climate, you will need to put a pipe over the cutting edge, or use some other trick to prevent scraping the gravel off (standard plow shoes don't always do a very good job as they want to furrow in unless the gravel is really frozen hard). This precaution will be needed whether it's a front blade or rear blade. The whole trick will be removing the snow sufficiently "well enough" with minimal disturbance to the gravel. So in reality, driving over the snow before a rear blade hits it won't really matter and might even help.
If you are somehwere where the ground freezes hard and stays that way for a long time, you might have an easier job. And in those climates, people often want to establish a "plow base" of packed frozen snow over the top of the gravel.
I have a gravel drive and can generally get the snow cleared off with just a thin layer remaining. Here in VA, sun takes care of the rest quickly, but if it's really cold and doesn't melt off, it packs down and makes for a decent driving bases. Normally it will thaw again within 2-4 days.
This is a fairly typical result after clearing with a rear blade and pipe over the cutting edge:
I tend to clear in two passes, out and back, one on each side of the driveway. This avoids running down the very middle and scraping off the crown in the gravel.