Sexygirl
You are of course right.
35ft all engines and dry runway. 50ft is the landing screen height.
Nevertheless, I still think that it comes down to the likelyhood of which condition is more likely: All engines or Engine out. The more likely case has a bigger safety factor build in. That is where the 1.15 factor comes in. So sometimes the all engine net TODR can be larger than the engine out one, especially 3 or 4 engined jets.
Cheers
Arnie