I have a good OTA install, but I did it myself. I've had OTA digital for 3 years now and when I got Voom, the guy took one look at my big hurkin antenna then took a look at the little Stealth and said "We'll use your antenna".
My signal is up in the 70's and I never have a reception issue.
As far as channel mappings go, Voom put 2 channels in the Guide that are very low power and only available in Portland and since I am about 25 miles from the towers, I don't pull them in but it's no big deal, one is a religious channel and the other is a PBS channel. I can get the religious channel in analog if I choose to, but I would never watch it anyway.
As far as all of the regular channels, I get them all and have good strength on all of them. We are fortunate in Portland that all the transmitters are on the same hill so we don't have to worry about direction.