Sorry, but I beg to differ. I have personally seen a major difference in growth rates between mousers and rat eaters (both on a 10-15% body weight diet). Our rat eaters usually grow at a much quicker rate and have better overall body mass. Mousers we've had are usually slower growing and tend to be a lot lankier. You can get all scientific and quote nutritional values done in some lab, but coming from first hand experience and seeing the real life results, those numbers don't mean much to me. Other than that, I'll second what you have said. Start small and scent.
AKedit: Tessa, check out Big Cheese Rodent Factory. They will have what you need.