Nevertheless I have tuned in 107.9 in the car in parts of Richland County and the HD can even lock on at various locations. One of them at the Columbiana Mall along I-26 where I have shopped because they have a big Belk men's dept, and there is a Rush's burger joint in the neighboring shopping plaza. But as you get closer into Columbia there is indeed a LPFM religious station that will interfere. So you can tune to 1110 as an option to fill the gaps in the fringe, which is why I wish they would continue the simulcast.
Columbia is a geographically large, sprawling city that has tendrils which go out into Lexington and even Kershaw counties. The area you describe is on the far northwest side of town where OOM stations can often be received, they've recently erected a city limits sign on I-26 with our very attractive new city logo. I only have a small portable HD radio and haven't had it out in that area yet.
I live in the northeastern part of Richland County (my property isn't within the city limits, though there are such tendrils out my way too), just a little bit shy of where you can receive Charlotte FM or TV stations reliably (curiously, there is a final knife-edge to my south that enables me to get WTAT and WCSC with the Televes DATBOSS about 60% of the time). WBT-FM 107.9 cuts in and out depending on how straight a shot you have to that pesky LPFM in Lexington. Even W278CY on 103.5, WVOC-560's LPFM sidecar, can get overtaken by WEZL Charleston if you get down on a certain side of the hill.