That data and all the pretty graphs Golden Cheetah or any other software generates isn't going to tell you anything unless it's somehow couple with your perceived exertion at those cadences. On a given ride if I'm warming up or going easy my cadence will naturally be lower than if I'm doing a threshold interval. That doesn't in any way imply, however, that I'm not capable of putting out power at lower cadences.

I think you're going to need to do some of your own tests. One of the interval sets I like to do is 6 x 5 x 1 @ 106-108% of FTP. That's 6 - 5 minute intervals with 1 minute rest between intervals. A few yrs ago I tried varying the cadence during the intervals. I didn't notice a big difference and have attached a plot of my data. The blue trace is cadence which I varied from 77 to 100 RPM. I think my HR was a little higher on the high cadence interval but it's a hard to tell how much as my HR normally goes up from intervals 1 through 6. Yesterday I did a similar set and wasn't paying attention to cadence and it was around 94-95 with an avg power of 310W, so I assume that's my preferred cadence at that power. I have no doubt that I could manage the same power, however, at anything from 80 to 105RPM.