I use both methods...
I use the X45 as my throttle. It is programed with a saitek AH profile for all my buttons and rotors. inside AH, I set the large thumb rotor as my elevator trim axis. The settings inside AH over ride any setting the saitek profile had assigned for a particular button or rotor. The rocker is my aileron trim and it uses the saitek profile. The difference being when I stop pressing my aileron trim, I want it to stop where it is at while the vator trim will recenter when I spin the rotor back to the notched center...
tip .. I use a X52 jstick with all of its buttons and hats assigned inside AH. I use the big thumb button to toggle COMBAT TRIM on and off. CT is the secret to quick and easy trimmed out flying.