When I'm using mine to roast chicken or pork, I usually add a 1/2" of water to the roaster oven. It seems to keep the meat moister.
I have done an entire meal in a roaster oven - potato's, veggies and meat. I microwave veggies like carrots and white potato's for 5 - 10 minutes because they are harder and denser than most veggies and take longer to cook.
As long as it's not windy outside, you can put the roaster oven outside to cook your meal on a hot summer day. That's not quite as wonderful as barbecue, but it works.