Your going to love the Iwata HP-C. I got my self one for christmas a couple of years ago after replacing my old Aztec 470. The Iwata is easier to use and more consistent, and easier to clean. I never missed the side cup. On thining it is a good rule of thumb to thin your paint to the consistiy of milk. But of course it depends on what type of paint you use and what you are trying to do.