My point was simply that you can only know how fast you will lose airspeed if you try it. The glider example was added to show how fast an extremely efficient airframe will lose energy. A powered a/c "... in the same situation ..", i.e. a steep climb, would lose energy at a frightening rate; lesser climb angle = slower loss of energy. How much slower I have no idea - but nor does anyone unless they've tried it (as I see you have from the preceding post, but of course that's only accurate for the type aircraft you fly I would have thought - would it be true for e.g. an Extra in full climb?).
It is worth noting the point made by Mark1234 and poetpilot about the difference between normal flying attitude and normal airspeed during a pushover. The risk in turning too early is a potential gotcha which is always a surprise to pilots who've never experienced it. Not one to try without an instructor on board.