Hmmm, let's back off on the name calling and insults. Jag is right in general.
Increasing compression:
1) decreases reliability in an exponentially increasing fashion
2) increases heat to the piston, head, and cylinder in an exponentially increasing fashion
3) increases power in an exponentially diminishing amount
Where I (and probably others too) would disagree would be with fixed numbers as definite barriers.
My KTM 125 is running about 150psi and runs on regular octane fuel for many years.
My KTM 300 is running at about 165psi and has been for the past 15 years. That is reliable!
Pushing the China Girl into that range will likely assure a piston and cylinder life of well under 1000 miles.
I would agree with his 135psi pressure as a very rubbery line of where you start to lose reliability in the China Girl.
Let it be widely known, I have great reverence for St. Gordon, but as mentioned, that was 1973 (44 years ago!). Much has changed in metallurgy since then. Even the Chinese are making better cast pistons than we were using back then. I know, I was blowing them up!
Play nice guys, and have respect for each other. I have great respect for Jag and the work he has done. All the points I am reading are valid, but the harsh way many of them are delivered grate on my gentle nerves.