Indeed the WL-20 is not as good a unit as the more expensive ones such as the Shure. I'm using the WL-20 in place of a Line 6 G50. But I like the WL-20 as it sounds good and works as well as I need it to, it has rechargeable batteries, it's a much smaller solution, and I don't have to fool with the setup of the G50 RX every week.
One thing to watch on the WL-20 RX, the blue LED. If it blinks while you're playing, it's indicating dropouts, and the units need to be paired again. I see this from time to time, but the dropouts aren't usually bad enough to cause any issues. The Line 6 G50 has had zero dropouts. I'd probably use the G50 if I could leave the unit set up all the time.