Hmmm....well, a drop will most certainly not ruin your fletching. I doubt they are more accurate though. Those WB's are darn good rests. I believe a drop will help with broadhead flight. No contact is always a good thing. You will also gain a little speed with a drop, somewhere around 3-5 fps.
The one thing I really like about a WB is it's simplicity. Very simple rest, no moving parts, not much to go wrong.