Hey
I went with a 4x4 tent. I only use 3x3 of the space. 400cmh veg and then a 600hps to flower. After this run i am gonna try nine 3.5 gal rdwc buckets in there. The extra space around i consider "breathing room". I can get all the way around my plants inside the tent. Most hydro is fairly stationary. It seems real important to be able to access all things inside the tent without dragging stuff out. Think maintenance. Slide around the plants and maintain. How are you going to grow your plants???? Two 5 gal plants would make a great trainedlstfimedsupercroppedpinchedbushyscrogbush....Four 5gal would be better imo. couple cents....
I think I am going to go with the 4x4 tent, throw either 5 or 6 buckets in there and run them all from a rez. I plan on using the 600 to veg and then add the 400 to flower...