Thanks for your replies.
I did try this in a box and the only time I could see myself holding back the A/T in a FLCH CLIMB would be to comply with an ATC order like "xxx stop climbing now and maintain 3000 feet" or TCAS or even windshear. Besides that I have to check if the box behave exactly like the sim and by looking at FCOM and AMM this point was obscur.
Happy landings and safe flights.