As one that uses multiple bodies I think adding a second body is a great idea. The D5100 should fit your needs very well. You can even use it for more serious shooting. The only downside to the D_000 series bodies is they don't have AF motors built into the body, don't have a sub-command dial, and they don't have dedicated buttons to quickly change settings. If you won't be using it as a second body when you are under the gun, there isn't a downside. Good Luck and Enjoy your Nikons!