RE: Should I sell the Super Cub?
Landing is one of the hardest parts of flying RC. I've seen many guys in this hobby that can fly around pretty well, but screw up the landings more often than not (including me a few years ago). This can be made more difficult in a simulator if you have a hard time with depth perception and judging altitude looking at the 2D computer screen. And FMS doesn't have the high quality graphics that other sims do, which can help give you that 3D "feel" on a 2D monitor.
Different planes will have different landing characteristics as well. Some can glide in slowly with no power, some need some speed and power or they'll tip stall. From what I've seen & read about the Super Cub, it is a relatively easy plane to land. I wouldn't be surprised if you find it's actually easier to land your Super Cub than some planes in the FMS sim.
For your first flight, make sure you have plenty of open area with no trees (or other obstructions to hit), and make sure there is little to no wind. This will make your maiden flight much easier and "uneventful".
As mentioned above, the Super Cub was designed for beginners with no experience, so if you put in several hours of sim time before your first flight, you should do fine. The main thing to learn in the sim is how to fly the plane: away from you, towards you, overhead, inverted, etc. Knowing which is right/left or up/down when the plane is in every possible position is the first thing every newbie must struggle to learn, and a sim teaches this quite well.