Thanks for the kudos. I thought of one more thing. With a quad, and especially if you have larger props (like 10" instead of 8" or 9") there will usually be some coupling of pitch/roll to yaw, regardless. This is because the copter must yaw by spinning up one pair of motors and spinning down the other pair. The motors spin up as fast as the ESC can push them, but they only spin down as fast as friction can slow them down. The net result is that the force from the motors spinning up is not exactly equal to that of the motors spinning down, and the quad gets somewhat disturbed. Also, the motors spinning up may not spin up at exactly the same rate, and depending on the PID gains, the FC may not compensate quickly enough. Bottom line: if, when you yaw aggressively, your quad becomes somewhat disturbed in the pitch and roll axes, this doesn't necessarily indicate a problem with your FC placement. You may just be experiencing one of the reasons why some people prefer V-tail quads or tri's.
If you do have a problem with your FC placement, you should only experience it in autolevel modes. With a rigid body, all parts of the body will experience the same angular change over the same time, so the gyro should be unaffected by placement on the body. Since the Acro mode only uses the gyro, FC placement shouldn't affect performance in Acro mode. In autolevel mode, FC placement off of the CG will result in pitch/roll coupling to yaw input, as previously mentioned.
A final thing: when I say that FC placement doesn't affect performance in acro mode, that is ignoring the effect of vibration. The CG of the copter is where vibrations will be minimized. The further from the CG your FC is, the worse vibration it will experience. But in terms of "false input" (e.g. yaw coupling to pitch/roll), the gyro is not affected in that way.