I have a Skyline and a Supra. Love them both. So far no problems with either one. Some of these cars have had quality probs, but it's just luck of the draw. I'm sure that the cars are built on the same assembly line no matter which body ends up on it later. Just get what you like and have fun. Keep your receipt. If it breaks, take it back. You tend to read about a lot of probs here on the net, but there are lots of others having fun with their cars and not posting.
As for wheelbase, I believe the RSX has a shorter one. I don't believe it that would be a problem or a blessing, really. Maybe a bit quicker to turn, but we're talking about cars that are only 6" long to start with. Just get one and enjoy.
As for me, I just got through running both of them on the porch for a while this morning. I find it relaxing. My wife and neighbors think I'm a little nuts since I'm 35 years old and still play with toys.