Yea, I use RD for just about everything when cooking for parties or other projects.
As for certain seafood, yes you can get it there cheap but it will not match the quality of getting if from a good fish store. I had a project where I needed scallops and bought a 10lb bucket which I wound up giving away or using personally since they weren't something that I wanted to serve. Clams and mussels are a steal there as well. They only way I've been able to get them cheaper is taking the boat to some of the clam beds around here.
I also have a bunch of their pots, pans, cooking tools everything. You really can't beat the prices.