Following recent boredom, I decided to give these a whirl. Much to my surprise, the results were very favorable.
Every time I call out a Spy Plane, it's seldom effective with the abundance of Ghost. That said, RC-XD's are very cost effective, especially when you have a good idea where people usually are (like chokepoints, overlooks, etc). Not only that, they're one of the best tools to dislodge campers, and Flak Jacket rushers who attempt to annex objectives. Being a Domination player at heart, this aids me greatly. Sure, one could say the Spy Plane helps the team, but so does the RC-XD when used against kill whores. They certainly beat the risk of dying several times to tenacious spawn trappers.
Say what you'd like, but it does provide the uses.
I've only used it 73 times, which is on the bottom 2 of my killstreaks used, and that's because I always get them through care packages. Don't really like em, and it doesn't bother me half the time because I always use Flak Jacket.
Rc-Xd gives you 1 free kill, spy plane can gives you like 5, and It will help you getting another higher killstreak, but you don't must trust 100% on your spy plane, rc-xd is btw really annoying, its a streak killer.