Yes, they are perfect for chasing down waves or covering a lot of ground. Everybody in the lineup was on regular looking shortboards or step ups and I easily caught all the best and biggest waves. They paddle insane and can catch waves you think you can't. While they are designed for surfing bigger/steeper waves, I find that they also have some decent glide to them and they are still fun when the waves are smaller or at the end of the bigger waves. A step up egg or even a step up fish is a good description for them. I've gotten double overhead kegged on mine and done round houses on waist high waves as well. I'm 6'1 and mine is 6'6 x 38 liters.
As far as versus a ghost. Ghost would be for ledging or barreling waves where you sit in one spot and are trying to knife it or take off under the lip. FCD is for a bigger playing ground, lots of current, shifty peaks and/or fighting a crowd. I'm a little more confident on my F-Rocket because it paddles so well and can get me out of bad situations faster than the ghost.
If I found a 6'0 or 6'1 F-Rocket used, I'd sell my 6'1 ghost.