My personal objective in participating in this discussion, and possibly in future trials as well, is to better understand the mechanics of the maneuver, to get a better understanding of the factors involved, and to get a better qualification of turnback height.
Right now, depending on who you talk to, the "no turnback" height is somewhere between 500' and 1000', without further qualification or any consideration for aircraft performance (MTOW or not), circumstances (Wind, altitude, temperature), runway length/layout or anything.
I know there are aircraft that will not be able to make a successful turnback from 1000' (a fully loaded DA40-TDI for instance), and likewise there may be aircraft that can be turned back at less than 500' in the right circumstances.
If, at the end of this exercise, we end up with a series of graphs, guidelines or something else, that allows you to calculate a realistic turnback height (including a safety margin, and which takes into account reaction times and assumes only moderate pilot technique) for your specific aircraft and circumstances, then I think we've done a good job.
But obviously below that calculated turnback height you can't turn back and still have to land ahead. It's only above that height where you are given the option to turn back, or to land ahead. And "land ahead" might then still be a better option.
When you really think about it, is it worth the effort training yourself to turnback?
Tough question, but probably more or less comparable to the question of whether it's worth the effort of training yourself to do, for instance, short/soft field take-offs and landings.
If you always take off from hard and long runways, maintaining soft/short field skills may not be all that important. And likewise, if you always take off from airfields that offer plenty of land-ahead options, it may not be important to acquire the turnback skills that the eventual procedure may demand.