Too bad that's a bunch of BS... I hate it when people spread misinformation. I'm going to do something different here and talk actual real world experience, rather than just make shit up and pass it off as fact.

Here's what I posted on Acura-Integra.com about this very same subject:

In my experience, the AFC setup really isn't all that bad, if you do it right. I got a real good deal on a VAFC from a friend, so I planned on using it for a short period of time (I was anxious to boost!), and then getting to a standalone. Being that I regularly road race this car, my needs are considerably higher than most, but I found that this setup really does work great for me, so I've had less motivation to upgrade to a standalone.

My setup is a B18B @ 7 psi with a VAFC, 450cc injectors, Walbro 255 lph pump, tuned to 12.5:1 A/F and base ignition timing retarded 2 degrees. I've been running it that way for the past 10 months and have put this car through more hard use in that time than most cars will see in their entire lifetime. Zero engine problems and it is still running very strong. I don't even know how to begin explaining all of the abuse that this engine has seen, but it suffices to say that this setup has proven itself many times over. Yes, it's a hack, but that doesn't mean it can't work well. Afterall, Hondata or Uberdata is a hack too... just a more direct one.

The timing issue really isn't that big of a deal... You're right that the timing is getting advanced. How much really depends on what ECU you are running, boost levels, and what the AFC is set to at every RPM. Your example assumes the AFC is set to -43% at all RPMs and throttle levels, which is unrealistic if you have 450cc injectors. That would be very lean and it also exaggerates the difference in timing. Real settings for 450cc injectors are typically around -38% (idle) to -35% (boost) on the wide throttle map.

-36% would be a realistic average for the AFC adjustment under boost. By your example, that would mean that there is really only a 2-3 degree advance in the timing under boost. You can easily compensate for that by retarding the base timing on the distributor. This obviously isn't the best ignition setup, since I have little control over it, but it happens to work out in my favor. It's really not the end of the world if you have a little ignition advance under boost anyway. I've never heard any pinging or knocking, and I'm sure that if it were a real problem, my engine would have blown up long ago. I've taken it to the road course 9 times with this setup and many of them were on rather hot days, so if it were going to have a problem it would have.

A good standalone really is the ideal solution, but the AFC is inexpensive and happens to work very well. My only complaint is that it bucks a little bit when you're crusing at like 35mph and let off of the throttle, but it's only a small annoyance.