A big difference in what way?

Sorry... in the health of your tank

In the cost of food ya, but nothing else. I don't see any benefits, but that doesn't mean there aren't any. Who knows?

it just seems to me to be more natural.

... just wondering would fresh seafood run the risk of contaminants?

I tried Kien way and i made a mess so I just don't do it anymore :-)

Ask Michka

I've followed these instructions in the past but I dont anymore for a number of reasons.

Do-it-Yourself Frozen Food
by Steven, Pro
http://reefkeeping.com/issues/2008-01/diy/index.php

I too used to make my own as well but I tore up sheets of nori and added it as well. I dont mind buying food now. Much happier spending the money than having the head shaking and rolling of the eyes from my wife due to my poor cleaning skills. It's messy. She's happier too.