I think switching the offenses and defenses is a mistake, for two reasons:
1. My guess is that, if you stick with one o/d combo, your players will progress at least a little bit in IQ. This will give us some insight into "baseline" IQ growth due to starts / PT. This is useful info in and of itself. If you switch around, you'll pollute the data.
2. Switching o/d will give you an advantage, because it will make game-planning against you very difficult. Obviously, this will increase the chances that you will be competitive, but it kind of takes this from being a scientific study (where we're testing just one variable) and makes it something else (because you'll be testing multiple).