My view is that one should set the elevator trim so that the aircraft climbs at Vx.
Some types Vx results in such a steep pitch angle that an EFATO requires a real push to get the nose below the horizon to accelerate to a controllable glide speed. Typically they will have a big spread between Vx and Vy. The Bonanza and Super Cub come to mind.
Some older twins published Vx below Vmc, this was before the concept of Toss.
Some examiners like to see Vx for the first few hundred feet of climb, but my SOP is to use Vy, and then cruise climb above 1,000 AGL.
