Depends on your set up. But I don't think now would be a good time unless you keep a light in the coop and winter is coming and production will drop.
If you only have 1 coop you'do probably be best to test one feed at a time, maybe a month at a time. If you have 2 or more coops then you could try different feeds in each, but remember even each chicken could have different needs, and it would be best overall to test each feed through each coop.
Also depends on the parameters of your test, are you looking for less feed=more eggs, stronger shells, overall taste? Some of those can be solved by coop changes for example feed waste my feeders were on the ground but recently they started dumping the feeder over when it was still half full. Hanging the feeder has prevented this as well as extended the overall feed consumption from 2 days per 10 pounds to 4-5 days per 10 pounds.
If your main goal is taste, treats and free ranging will effect your results and should be limited or stopped during your trial