With studio lighting anything you imagine is possible. Best investment I ever made!
Some good advice, if you want to improve your photography then another camera, or some other lens is not going to do it. Rather invest time in learning how to light your subject better, I guarantee that will have a major impact on the quality of your photos, much more than another high priced f2.8 zoom ever will. The temptation is always to get that new specced dslr with the more megapixels and higher frame rate, or that new VR version of the same lens you already have, but unless you change the way you light you are wasting your money. Next time you have bucks to blow, go get a speedlight instead, or a nice softbox, wireless triggers, light stands, umbrellas, heck just about anything but yet another camera body. Be strong, resist GAS, you can do it! ;-)