I like the idea of GPS assisted dead drops for moving bulk, or for doing local deliveries of small amounts in a small area. Mail is still pretty safe though, I might actually trust the mail to move a kilo of coke more than I trust some random fuck on a .onion site. In any case the buyer should not give the drop off point or else they could be LE and bust the delivery person, delivery person should pick the drop off point in an area close to where the buyer suggests (by close I mean within sixty miles or so). Biggest risk is that mostly LE will sign up for the long distance transporting service, to bust customers, who are all going to be bulk dealers. For localized dead drops, where vendors deliver inside a local region (probably big cities would be best), I think the idea is pretty solid though. It avoids the need for mail transportation which drops seizure risk substantially, keeps anonymity for the vendor (really it increases it as they can drop product off literally at countless locations) and increases anonymity some for the customer (picking up from a random location the vendor picks is probably even a bit safer than using a fake ID box).