I went from the G700 to the G503, and I wasn't really expecting much to change, but everything felt much more precise even before I adjusted my DPI settings. Now, before someone says, "Well, the G700 is a wireless mouse, you dolt!", I used it with the cable plugged in, which allows it to send all data through USB. It was effectively a heavy, wired mouse.
I think my only complaint is that I kept noticing my DPI setting would get changed. Now, I don't know if I was hitting a DPI button without realizing it, but it would really throw my aim off in games. Fortunately, the DPI settings are fully customizable to the point where you can remove options.