I agree with Jocephus... you will get a ton of opinions on this one and there are so many ways to set up tanks.
the only dig I can see for a wet dry is running bio balls. I dont think they add much to a reef system. IMHO just replacing the bioballs with Chaeto and putting a clip on lamp on the outside is a fine conversion of a wet dry for saltwater usage.
Tat2- after seeing your system I think that adding cheato to the compartment underneath your chemical filtration(the bioball compartment) and keeping your skimmer running should be a good way to go. in essence you will then have chemical filtration, a refugium with biological filtration, and mechanical filtration-all types available. I forget, do you run charcoal? personally I run polyfilter and charcoal.
oh, YGPM
Cheers,
Eric