I have an ES5 if you are interested.
Also I own an UERM and have a UE 18 pro on order. Haven't tried the UE 18 pro yet but should have answers soon.
But I would agree, the ES5's would likely be the best option if you want some of that Guitar to come a live and her voice to really resonate with you.
The UERM wouldn't really do a specific taste a lot of justice. Although I don't listen to a lot of country when I'm flipping through my billboard tracks the occasional country tracks definitely leaves an impression with the ES5's ability to capture the realness and tender vocals of the artists.
With I could give you the UE18 perspective... I remember the demo unit having a hump in the bass section.. but that is about it.
PM me if you want to buy a used ES5 with all accessories.