As a matter of fact, I am using LOP only on long flights (2 to 4 hrs) and ROP on short ones.
As you said, single pilot IFR ops don't leave much time to keep the eyes on the engines clocks.
I am flying the Seneca of my boss since 300 hrs, among them, I will say, 150 are LOP.
What you mention about the Malibu is not totally surprising but I am not sure ROP totally solved the problems, since Malibu have always been known for engines problems ( I was told not a lot of owners bring their engines to the potential ....)
Anyway, I appreciate your contribution to this somewhat complex , but interesting subject.
Thank you all.