I have two of them and have used them for the last four years. Actually, one is a Big Apple and the other is a standard GCF incubator which I modified so that the fan and heating element run separately. If the fan and the heating element are not separated and run on the same circut, the fan can overheat if used with a proportional thermostat (a fire hazard) and the fan will shut off when the heating element is off which can lead to temp gradients Separating the fan and heating element alows the fan to run all the time and the heating element to be conncted to a proportional thermostat. I actually got and modified the GCF before I bought the Big Apple and found out that they did essentially the same thing.
I use 6.5 quart rubbermaid containers and each incubator can hold 9 tubs. I made shelves out of the plastic lighting egg crate material and it works fine and allows good air flow.
These incubators and set-up have worked well for me and I have never lost a clutch due to the incubators. Mine hold temps within 0.2 (2/10ths) of a degree. I dont think you can go wrong with these.
Having said that, I plan to make a room incubator this coming year with separate and redundant heating and air circulating systems connected to separate electrical circuts. Having 9 clutches at risk for a catastrophic failure (curcut breaker trips) creates enough distress. Thinking about 30 clutches at risk would give me ulcers if there wasn't "bullet proof" redundancy built in.
Good luck
Grant