IO
At the risk of being pedantic, your description of a short field take omits the difference between clearing an obstacle or not.
For the former, the climb at Vx must be maintained until safely clear of the obstacle (having first caclulated that this is feasible), whereas if no obstacle is involved, 50' is a safe height to release the back pressure and start thinking about accelerating to a safe speed/cleaning up (if necessary) and looking for Vy.
Reference is
Airplane Flying Handbook - Google Book Search
Not trying to be smart, as I agree with you in the point you are making, just to be absolutely clear for others reading who do not have your considerable experience.