Going back to the original question, I used to know a pilot who spent a lot of the war in a POW camp because his Blenheim wouldn't stay in the air on one engine. "I would have got home if it had had feathering propellers" was his comment.
I believe that Coastal Command Wellingtons were so heavily overburdened that losing one engine was very bad news.
And I used to be flown out of Wilson Airport Nairobi in a Partenavia P68 twin which I was told would level out on one engine at an altitude considerably lower than Nairobi if it was fully loaded (It was the same ex-Blenheim pilot!)