We use them all the time. Recently we have been using the Hunter WRC with good results, due to the fact that Rain Bird doesn't currently offer a wireless WRC. Line of sight is a CYA term. Rain Bird made one for awhile, but they pulled it some time back due to some issues and have yet to reintroduce it. It really seems that Rain Bird's R&D dept. has missed the boat in recent years. They seem to be the last ones to come out with the next big thing.

All Wet
Texas Licensed Irrigator #1897 since 1984

So they work like a transmiiter, say like a garage
door opener. Transmitter and receiver. Receiver
will be in garage with controller and transmitter will be
outside on gutter. No problems?????

We install them all the time. I always put the timers in the garage and they work fine. We usually install the ones from r and d enginnering. They say the batteries will last 5 years, we are lucky if we get 2 years.