Glad to provide some real world experience with good product that can stand alone. The ANT751 is a lovely compact unit that gives a lot of bang for the buck with fair signals and better that are line of sight.
Much of the criticism I've read on the ANT751 is due to unreasonable expectations with it. Working with 1 or 2 edges isn't the domain of the ANT751. Neither is single digit db signal strengths.
I did want to pass along to David, I did a couple searches on the real channels 19 and 21 from the translators located 6.6 miles away. Rabbit Ears information has one as a CBS retransmission from SLC while the other is the ABC stations retransmission.
Translators sometimes are a tricky thing to isolate what their programming is until you actually have it on your TV. Why? Translators can be station owned or local community owned. Your best bet is to use sites like rabbit ears and search out each call sign to see what the latest information is on what the translator in question is carrying. From my days in television, I knew the Salt Lake stations had and still have a large translator network to cover Utah with programming.
With only a look at the first two translators, it appears a reasonably safe bet that most of what you receive, your parents will receive too, they'll just be catching the signals off the translators instead of the originating transmitters.
Let us know! I feel pretty confident the ANT751 will serve you well on those translators. It's a pretty ideal situation for the little antenna if you have a good LOS.