I think a likely reason (apart from cost and inertia) that we haven’t seen TOPM appear on the flight decks of aircraft from the major manufacturers is that it may be more difficult than it appears to design something that cautions when appropriate but doesn’t give false warnings. What sort of margins are there to play with? Considering that for maintenance reasons, most performance software tries as hard as it can to make a balanced field and that you’d be lucky if the aircraft actually weighed within 1% of what the load sheet said, it might be that the warning envelope would overlap with “normal” operations. Add in the variables of where the aircraft actually starts its takeoff run, contamination, variance in wind and temperature and it might be a non-trivial task to algorithmically discriminate between OK and not so?