Okay, first update... somewhat as I feared, the large Yoke/Collar is slightly too big for the G&P XL. It fits, but the velcro on the shoulders are "too far forward" (in relation to the vest) by about 1 inch.
So between that and the groin protector, I feel it's safe to say the G&P XL works out to Medium on a real FSBE AAV.
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