Phil Irving wrote a cam article for MPH back in the 80s?
I can't recall if it singled out the singles, it may have been mostly a discussion of cams for the twins. I think it is still worth a read.
The gist of it was that, with twins,MK1s are for touring, Mk11 s are for racing.
He was perplexed that so many people were installing his race cams on bikes used for two up touring etc. Not that the MK11s wouldn't work, he just saw it as a 3-4 k rpm detune that brought with it a bit of extra valve train stress. Most touring bikes spend about 99% of their lives below 4 k rpm.
Irving said the advantage of the MK2 was only at high rpm that most road bikes never see, or only see for a few seconds now and then.
When pulling up a long mountain grade at normal road speeds and sub 4k rpm, he said the MK1s had the advantage.
My understanding is that MK3s are MK1s with quietening ramps added.
Best to find the actual MPH article, I may have remembered it inaccurately.
Glen