If you are shooting big, fat Lincoln Log arrows, there probably aren't a whole lot of advantages to using a dropaway rest. However, if you shoot skinnier arrows with helical or offset fletching, a dropaway rest is clearly superior. Fletching contact is the the biggest tuning issue with skinny arrows, and a good dropaway that is properly installed will totally eliminate any chance of it.
Good point....and as Jeff pointed out there are some definite advantages to drop aways though they do require more tinkering, in my opinion, than a typical prong rest.
Personally, I am still looking for a drop away to fall in love with. Out of all of them I still like the size and design of the Trapdoor the best (no linkages) though its reliability leaves something to be desired.
Conventional rests on both of my bows. Heck, I might even try a B2 Biscuit this year.