[RKDinOKC]

The short answer is Yes.

The cards are the same for 5SE and 6. Changes on 7. T-mobile is compatible with ATT and Verison as well.

You should be able to restore his data to the newer iPhone before you send it to him. The SIM card only changes the carrier information not the other data on the phone. People even change SIM cards without turning their iPhone off to change between carriers or numbers though Apple recommends turning the phone off.

When getting a new iPhone have always backed up to local computer, then restored to the new iPhone using the computer. Then I remote wipe the old iPhone.