Most companies on this side of the pond do not call out the FMA. I don't gain anything from calling out the FMA that simply reading it doesn't give me.
I would suggest some advantages of reading the FMA out loud include:
1. You have to read the FMA to be able to enunciate it, so having to say it it means you have to read it;
2. Your colleague knows that you have read it;
3. You and/or your colleague may pick up an error in your read-out which could be caused by a genuine misreading or the correct reading of an incorrect FCU input;
4. Your colleague may not realise that the FMA has changed until he/she hears you say it. This will help to increase his/her SA;
5. Any standard call also serves as an incapacitation monitor. If you fail to read the FMA changes, your colleague can challenge you and maybe start the incapacitation process.