For the average flier I disagree with trimming at full throttle...but the nice thing with our hobby is you can do what you wish.
I'll give you the reasons I trim at 1/2 throttle.....I want a tad bit of climb with power on....for if I add power that is exactly what I want to do is climb.....I cannot think of a single time where I reduce power to gain altitude.....trimmed at 1/2 throttle is "cruise" where I do most of my flying...very little input from me to fly straight and level....with power off I want to descend....lastly on approach I don't have to hold in alot of up elevator where if for some reason my thumb slips I didn't re-kit an airplane.
One of the advantages I see in trimming at full power is doing alot of aerobatics.....you don't have to be on the elevator as much on the down lines of loops and bowties.
just my opinion.....Good Flyin to all