There is an excellent thread pinned at the top of the Q forum for adapted lenses - click
here It's well worth a look and there are lots of sample images.
As far as a DSLR is concerned I guess it depends on your budget, the features that are important to you and your expectations. I have a K500 and love it, although some critics berate it for missing one or two features. Moving up the range there is the K50 which is well regarded for the money. HOwever, you don't have to go to to the expense of a new DSLR if you can't afford one. For example, I wanted a backup camera to my K500 so I recently bought a secondhand K-100D with the 18-55mm kit lens for well under £100 from eBay. It's only got a 6mp sensor, doesn't have live view and doesn't shoot video, but none of that bothers me and I think the results from it are excellent, especially for what it cost me! The big advantage I find with the DSLRs over the Q and other compacts is the lack of shutter lag. Obviously DSLRs will have a much bigger sensor than the Q and that, in my opinion, is far more important in terms of image quality than the number of megapixels a sensor has.