I switched from FFOF to Black Gold Organic potting soil two grows ago and felt the plants did better in the Black Gold than Fox Farms. I bought the Black Gold because there was no FFOF in Salem at the time and didn't feel like driving 120 miles roundtrip for one bag of FFOF so tried it out. It was $5.99 for a bag the same size as the FFOF ($17), and the plants loved the stuff.
Was in the reverse situation with my current grow, couldn't find the Black Gold organic, but was able to find a bag of FFOF, so bought it.
The plants just don't seem to thrive in FFOF as much as they did in the Black Gold.
Was totally anecdotal, except that the last 2 grows were all clones from the same plants, so the variations of seed genetics wasn't a factor.
Anyways, thanks for doing the experiment COF, going to be interesting to see what happens as time goes by.
Peace!