This sample C11 started life a good 30 years ago. I bought it used. It's optics were decidedly mediocre at best, rough, with pronounced "spokes" visible in the figure (specifically, the out of focus rings). Although I could indeed see more detail on Jupiter and the image was brighter, my old AP 6" F9 Starfire consistently ate its lunch in sharpness, contrast and, especially, what I call, image fidelity. To be honest, the reasons I bought it were that it was cheap, had an active cooling system and was not bad on deep sky stuff. And did I say it was cheap?
But the "ok" optics bugged me and I parked the scope for several years.
So about two or so years ago, at the urging of another CN's member, I contacted Celestron about the optics. They were responsive and after some negotiation, with a promise of new and better optics, we settled on a reasonable to me price, got a return authorization, packed it up and off it went.
A couple of months later, after they missed the return date, I gave them a call. Seems the scope was done but languishing. It went out the next day.
After set up, star collimation and a swing over to the Moon, it was immediately clear in the first millisecond (and I'm slow), this was now a muuuuuuuch better scope. Sure, like all SCTs of my acquaintance, focus was a bit touchy and the image did shift a little while focusing, but, unlike most SCTs of my acquaintance, the image was actually....sharp. Very nice really.
Later, I used this scope to experiment with adding a couple of layers of Reflectix to have better thermal control of the system. It works splendidly, significantly calming the scope's innards and significantly delaying the onset of corrector dewing. Very nice.
But it has been screaming at me to put it into DPAC and so I relented.