The program I'm doing called for seated DB military presses as well as arnold presses today. I used to always use some type of bench with a backrest while doing these, but after a few months of standing mil. presses, I decided to opt for doing them on the edge of a bench with no support. It definitely takes a lot more to stabilize, however, at certain points it felt as if just as much work was going into keeping my back upright as it was pressing with my shoulders.
To my knowledge the argument for not using a backrest is that it works the core more without one, therefore should it therefore be superior to the back rest version? Wanted to get your thoughts on the world of seated dumbell military presses.