The roasting pan will work to keep the russets warm, but the heating element may make the skin and the bottom of the potato dark brown, like an overcooked potato.

A couple of options once you bake the potatoes and remove from the oven:

1. Cool to room temp for about 15 minutes, refrigerate and then microwave just before serving. If doing this, be sure to pierce the potato skin in a few places so any steam can escape.
2. Place on a metal rack in the roasting pan so there is air circulation around and under the potato so it stays warm but does not discolor
3. Cool the potatoes, cut off part of the top, hollow out the pulp and mix with cheese or sour cream and other ingredients and place in the roasting pan to heat up to serving temperature.

Check this link out for more tips and recipes on baked potatoes: All Things Baked Potatoes