I just performed an A/B comparison of the AF9 pedals. I used a Strat clone with a significant boost before the AF9.
Both pedals worked well with single notes and chords. However, the Ibanez had more high frequency tones and sometimes sounded thin/brittle, especially in the HP Filter setting. The Maxon had a more full/rounded sound and was more pleasing to my ear. Even on the bridge pickup, the Maxon wasn't harsh.
Here's a decent demo:http://www.youtube.com/watch?v=rTs5gMC1l3U