I own a Nano 24 but it's hard for me to tell you the positives and negatives about it. I completely removed the hood and have metal halides and the pump was replaced with a pump that produces less heat. Overall, I really just have the tank.... I'm getting a Biocube soon though; however, I have heard the ballast doesnt last very long on it.
I have a stock Oceanic BioCube 14G. LOVE IT! I even like the protein skimmer that they make for it. The pump has a great out put as well. Definitely one of the better models I've seen.
The only con, is every 3-6 you have to oil the fan. I've personally had to do it and I know others that have had this issue. Some people never have the issue. It's not hard, but a little inconvenient.
Keep everything stock, even the protein skimmer.
Coral:
Torch, Blastomussa, tons of polyps, red lobo, birdsnest, tons of mushrooms, candy cane. The torch got huge and we have a 40G and a 155G so we just started adding more to the bigger tanks...
I really really love my JBJ Nano-Cube 24g. I have become a little addicted to it.... ok extremely addicted lol. I run it stock and I plan to keep it that way, I have seen some amazing stock tanks so I see no reason to dish out money for tank equipment when I can spend it on critters and corals. Check out the thread