My Revo (like most others) is almost 4oz. I have maple shafts that range from 3.5-3.7oz, and that is a noticible difference in terms of balance.
But we're talking overall cue balance. Shaft balance itself, the Revo is obviously lightest up front, whereas a maple shaft distributes that weight more evenly. However, even on maple shaft the least amount of mass is up front (assuming you don't have a 1"+ genuine ivory ferrule or something) due to taper - that factor is less noticible on balance than overall shaft weight.