they probably wont say a thing regarding the FMP, i had one of those on my BMQ and not a word was said, other than a couple of inquiries about where i got it. every course is different, but on my BMQ they let us use only issued kit as far as clothing goes. however the old rule of what they dont see wont hurt them does apply.
just keep in mind once u ge back to batallion or ur home unit or wherever ur coming from, you will more than likely be able to use ur gucci kit, most units are pretty liberal about gucci kit. i know with my unit no one gives a rats behind what u wear in the field, there are guys wearing brit or american camo. in the garrison however its pretty limited. my advice is to simply hold off on the purchases of more kit until ur course instructors/ chain of command back at ur home unit advise u on what u can and cant use.