Yes, I know not to fill up a card completely. That's how your card can either lock up or corrupt the images. Then it's good bye photos... not a good thing.
Why would you switch over to a different system if you already dropped so much money on the one that you currently have? Because honestly, it's not WHAT system you use to get the images, it's HOW you use the system. Anyone can have a great camera system, but without proper knowledge of how to use it, the images will still turn out crappy.
Getting it right in camera is the best way of doing it. Exactly why beginners should start with film over digital. Anyone can go in once the shot is taken and spend quite some time in PP to make it the way they want, but it's a hell of a lot easier to spend the extra time to get it right in camera (whether that be an extra 5 min or 30 min). It will save you a lot of time in PP.