A discussion point, from an "orange" flight safety magazine, same topic of use of Mayday/Pan calls:
"An engine failure, even on take-off, would not normally necessate a Mayday call, although further complications may well justify this."
Hmmm..... for me, in a twin-engined aircraft, if I get an engine failure on take-off, the Mayday pro-word would be getting some serious use! Regardless of the cause of the failure, by using Mayday, I am telling ATC (& other traffic) that I wish the airspace to be cleared (possible climb/performance problems - emergency turn rather than the SID?), & if appropriate, the runway to be kept sterile. Weather & performance considerations permitting, I will be landing back at the same airfield fairly shortly!
Apart from that, as mentioned on the "multi-engine failure" Tech Log thread, there are circumstances that could lead to imminent problems with the live engine, & I don't want to be the one to find them!!