There you go...all different growth rates!
Your 4 year old is a lot bigger than my 5 year old 'regular' redfoot. Kathrin, at five and a half years old, now weighs 938 g and measures 170 mm in SCL.
Her growth is very smooth (see picture). Would you mind posting a picture of your a lot faster growing regular redfoot?
I will post carapace pics of my other 3 guys / girls in the next post, so we can compare growth patterns!

Gaby