Here is a pretty good article from Seascop that discusses a comparative study of different filtration schemes.

http://www.marineland.com/seascope/ss2003_issue2.pdf

What I got from this is that the best method for nitrogen control is having macros and lots of live rock to use the ammonia before it even goes through the nitrogen cycle. A definite plug for refugiums. The other thing I got from it was the importance of a good skimmer for TOC control.

Gary