I've got the model 1 on my reef ready 55 and I love it. I still use the bio balls and
have never had a 'trate problem, mine stay at or right around 0.
I think most people pass the "nitrate factory" thing around as hear say. If you clean some of your bioballs every now and again with saltwater taken from your tank (water change water) you won't have a problem.
I bought the model 1 cause I had a 30 gallon tank and that was all I could fit in my stand. I ended up getting a 55 about 2 weeks later. lol
The build quality is wonderful and even with the model 1 I still have enough room for my skimmer and phosban reactor.
Hope this helps.