You also need to figure for how many people are in the room. I agree with SYSINT on the 2 system setup for two reasons. Not only will you have efficiency but you will at least have one system working when one breaks down which is probably important for the conditions you mentioned. Also you may want to look into what kind of control systems each contractor offers. You want to be able to check and set temperatures from a remote location and you should be able to set it so it pages you in case it gets above a certain temperature in that area.
thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!