I have N. elegans (male)...N. vlamingi (male)...N. unicornis (probably male) and N. literatus (female) in my 400.
First, the vlamingi and unicornis are, by far, the fastest growing...and probably headed toward larger overall size than the literatus and the elegans.
...and....yes, I'm concerned that they are outgrowing my system even though is a very open water reef layout. At almost 3 years old, however, they all seem very fine so far.
There are not many scuffles between the Nasos. They seem to be very laid back fish. When there are chases, they are quick and harmless...nothing like a scuffle between acanthuras tangs, which usually leaves marks!
It is interesting to me that most of the time, it is my female literatus that the other nasos seem to dislike. Honestly, she was an accidental addition that I wish I could remove at this point.