I couldn't take it any longer

I went back to the 800MHz image I stored on the N900. The difference when reverting to the stock kernel was to great. It was like flying first class for a month and then told you have to go back into steerage class... or worse, Student Standby.

Opening web pages from desktop bookmarks was the most painful.
I did run Sygic Maps from MHz and had it route me from Philadelphia, PA to Canyon City, Oregon, a distance of 3549 miles and it took 25.28 seconds. The same locations and route at 800MHz took 18.02 seconds.

This ^ isn't science, just a simple observation. From reading the Wiki and threads it seems that 805MHz is now being used by some. The reasoning behind these 800 vs. 810 vs. 805MHz settings aren't very clear and maybe it ain't science either.

Regardless, there seems to be some issues with all of the kernels after making a phone call.

I don't use my device as a phone so perhaps that is why I haven't had any problems @ 800MHz. The OP said he verified that he was at 800 using Conky before downgrading so it doesn't sound like the phone call bug was a factor in his observation as well.

But then again one of the existing overclock threads would yield more answers.