I'll be the first to say that only your eyes and what they see are what matter, but something ain't right.... Sub-channels or not, they still exist coming from the TV station. They're allocated "X" amount of bandwidth for (1) or as many channels and sub-channels as they want to offer. Insight is receiving the same signal, even if they're receiving it via microwave or fiber, the station is still outputting the same signal.
If you had tried just one receiver, you could certainly point the finger at it, but you've tried two....
Again, if you think they look better, that's all that matters.
I guess it could've just been the different inputs. The OTA was via DVI/HDMI whereas the Cable box was hooked up through components. It was almost too close to call, but subjectively the cable picture seemed to look just a tiny bit better. I also preferred the nationals (e.g. Discovery, etc.) over my cable compared to Dish.
Anyway, my point is that, at least in Central Indiana, Insight Cable has excellent HD picture quality. So whoever the original poster was can't really go too wrong either way.
Edgar in Indy