Don't buy in to the hype about switching from mice to rats, it happens but it's easy to get past. Carpets have such a strong feeding response that waiting out until they'll eat a rat, turtle, human leg, etc works just fine. I personally haven't had an issue switching any of mine, but i hear it happens. Eventually the carpet will get hungry and eat anything offered. Once they eat 1 rat you're golden. Congrats on the new carpet btw, once you're past the feisty stage you'll fall in love with their personalities.