BBJ
You're right, I thought the XV-15 was a piece of crap and it's follow-on, the V-22 is what you get if you combine everything that can go wrong with a helicopter and an airplane all in one place. Helicopters are a bunch of parts flying in close formation all trying as hard as they can to get back into the box they came in. You couldn't make the Casa fly in trim and besides if it has props, it belongs in the water...
All that aside, it's interesting to note that three of the original BBJ position holders, to include Greg Norman, never accepted their Boeings and all are flying GV's today.
The Chief Pilot of one of those departments is a friend of mine and a bit of a wag. He was complaining that if they got rid of their GIV for the BBJ, it would have a negative impact on flight department pay, in that there are a lot of Boeing pilots out there and not many Gulfstream pilots, so the Boeing guys will work for a whole lot less...