When you are just trying to make sparring sounds, a small set can be good. I'm a firm beleiver in using a large set, you can always rattle quitely, but It seems that its difficult to make TOO MUCH noise when trying to actully reproduce the sounds of a serious buck fight.

Even when rattling quitely, or tickling the antlers together, I think a larger set makes a sound more attractive to all bucks, large or small.