The big difference for me it's the hover height.
I tried once the -20 in the 139 from a 200' hover over the sea... I didn't like it!
If I'm at hover with less than 90% PI and below 150' I'd put 0º and pull until 90% rrpm hoping for the best.
With more PI and less height, I'll accept the ditching.
just my two cents.
Regards
Aser