Can I brown my turkey in my conventional oven first? That way, my turkey would have a nice brown skin, and I could continue the roasting in the roaster oven to leave my regular oven free to bake other dishes.
Since the roaster oven is so much smaller and has a fairly tight fitting lid, you are left with an environment that more steams than roasts in a nice dry heat. Because of that, you will be left with a not so pretty bird. Roasting it in the oven first might give you the color, but the slow moist cooking of a roaster oven will soften the skin to a less than pleasant texture. Your best bet is to cook the turkey in the roaster oven first, THEN roast it in a high heat in the oven to brown it up and crisp up the skin.
I would suggest doing the last half hour in the oven. Lightly butter the skin and turn the oven to 400°F to finish it off. The best part is, all the drippings will already be in the roaster, so you can pour that off and make the gravy while the turkey is finishing up. And if you have a large enough roaster, you can set it to low, throw in some of your side dishes and use it as a little hot box to keep everything nice and toasty.
I agree with Nick if you will be carving the turkey at the table.
For Thanksgiving, I always roast two turkeys at a time. One is pretty and displayed and carved. The other I carve before the meal and use in case the first runs out (we have big groups) and for left overs.
I always use the roasting oven for the non-display turkey. I have used it from time to time for the display turkey as well after roasting in the oven- as Nick said it doesn't brown as well but it is ok.