Actually, it's not the weight of the iron that does the best pressing job, it's the heat. The problem is, many light weight irons simply don't get very hot. So the trick is to find one that does and you'll get the pressing results you want without straining your arm and hand or worse yet, giving yourself carpal tunnel syndrome due to an overly (and unnecessarily) heavy iron. :D :D
I've found that many models of Black & Decker irons get pretty hot without all the weight.