If you're happy with Panasonic - as I am - there's no real reason to change. I have been absolutely delighted with my Lumix FZ-38. I'm believe the basic layout of the controls is similar across the Lumix range so you won't have a steep learning curve if you upgrade to another Panasonic. The Leica optics are pretty good too.
Unless you want an all singing, all dancing DSLR with features that you might never use and interchangeable lenses to lug around, I would stick with what you know and love, perhaps upgrading by one or two notches.