I sent your question to the manufacturer to be sure because I know the FX guns are Mil-Spec. Here's what they said:
Thank you for your email. Actually all (appropriate) Colt parts are interchangeable with our 1911's. Please advise your customer the parts need to be installed by a competent, professional gunsmith as many parts need minor fitting to function properly and safely.
ATI has also released recently the GSG 1911 .22LR pistol. This gun is only 80% compatable. The FX series is definately more universal (I have already seen many images online where customers have swapped out parts). But, like the MFG said, it's goodto have someone who is familiar with 1911s to do the work because as you will see when crossing componants on any 1911, sometimes minor adjustments need to be made.
Also be aware too, the FX series has a two year warranty against manufacturer failure and defect. If you were to change componants to something that isn't factory and it damages or breaks your gun, the warranty does not cover failure by non manufacturer parts.