Responsive Site Designer
The one big positive across these three applications is, if you learn how to use one of them, these skills migrate to the other two programs; as well as other Coffeecup applications such as Responsive Email Designer an Responsive Content Slider as the interfaces are very similar. This is clearly an excellent user interface strategy, which will allow for a GUI cross application rapid design environment.
My one concern is that CoffeeCup now have three responsive web-design applications to keep up to date. This may mean that after the initial frenzy of work to get the applications up, running and launched, that future updates are less forthcoming due to over stretching the development team?