I have a tel-tru on my Backwoods and I love it. I've heard good things about River Country and was thinking about trying them out on my Yoder. It seems worth giving them a try for the price.
I use River Country, have 3 of them between my UDS and 2 Webers. They are always spot on my Maverick, have never had to calibrate one of them although you can. Highly recommend and the price is great.