Probably anyone but Fletcher, all 3 others woidl remind players to drop their items and to pick them up for a cooldown reduction. Bush and Turtle are pretty much the same and players will quickly learn not to rely on dropping them as an isnt win, as for proxy a quick witted player would learn that they can ahoot their mines for some damage right after dropping them to surprise enemies.
The real question is, would there be a refund if one was turned into a starter merc?