The urban legend about trim was that it "added" to elevator deflection, when instead it works only inside the max allowed elevator deflection. Full up trim + full back stick gives the same deflection as neutral trim + full back stick.
As for the engine chopping, it's not very effective, but most of the times I've talked to folks that do it, it isn't for any advantage. Often they don't have a working throttle or any throttle at all. Several I've asked over the years said it was simply easier to map a key on their joystick to toggle engine on/off than to try mashing the keyboard for a throttle chop.
Practicality, not exploit-ism.
Food for thought.