My plants are grown in very strong light and so develop a nice red coloration and a neat compact rosette. It is possible that if yours were grown in lower light conditions the rosettes could be larger. I'm not exactly sure how large admirabilis is supposed to get in darker conditions. How much light do yours receive?
I've seen plants from different South African locations in other collections which seem to show a bit of variation (to mine at least)- whilst still identifiable as admirabilis.