I always weigh my kits regularly once they hit a couple of weeks old. I usually do this so I can catch any issues early since it is often hard for me to distinguish between small amounts of weight loss in such small animals. This practice coincidentally gives me some wonderful data to compare to my present litter. At 6 weeks of age, this litter weighed as much as my 9 week old kits did in previous litters.
At Convention, I spoke to an ARBA judge who feeds the Sherwood Forest NRF. He spoke highly of it and specifically mentioned the better growth rate compared to his regular feed when he test fed his meat breeds. I wasn't so concerned with growth rate (as long as it was normal), but I do see a definite difference. I wish I had measured wool growth at that age, although I'm not sure how I would have done that...maybe measure length, but density is important too. Anyhow, I am really pleased in their progress.