I get very strong signals on all of my OTA channels. I also have an H-20 with an AT-9.
Flipping back and forth it really is hard to tell if there is any difference between D* and OTA.
I used to be really into analyzing all the numbers especially in my Ham radio days. But after a while it became an exercise in futility.
The numbers would tell me the signal is garbage, Overmodulated, Standing wave out of whack, noise ratio terrible etc. Yet, I'm 5x5 on all of my contacts.
Now, get it all set up, tweak it a little and move on. I figure if it looks and sounds good, I'm not going to sweat it anymore. One less headache to cause.