I agree with Czech. The RTR's are nice in the fact that you can start runnig it right out of the box, but there are usually some loose screws that have to be tightened. With a Kit, you can be sure that everything is tight right away, and in the event that something breaks while you are running it, you will already know how to work on it. At first, it seems like a bit of an inconvenience to build a kit, but the knowledge that you gain, is well worth the time.