Quick summary: Both units work very well. The Skylink has a beep in addition to LED indicators. But, the beep starts as soon as the garage door is opened which is annoying. A 5 minute delay on the beep would be perfect for me. The chamberlain can monitor multiple sensors, but only has one LED indicator for all sensors. The Skylink has separate LED lights for up to four sensors of different types.If you want the beep, or want to know which sensor is triggered, the Skylink may be better. Otherwise, both units work great.---I got the Chamberlain first and installed in 5 minutes. The transmitter attaches easily to door with provided double stick velcro. The receiver (with green/red LED indicators) has to be plugged in, which does limit the choices for mounting. In one month of usage I had to reset it once because it was showing the garage door open when it was closed. As another reviewer noted, simply unplugging the receiver and plugging it back in fixed the problem. If the door is closed a green LED shines, if open a red LED blinks. Odd that the red LED is dimmer than the green LED.I thought it would be nice if it would also beep when the garage door is left open so I tried the Skylink GM-318. I got the Skylink today and it installed easily. I did have to fiddle with tiny dip switches on the transmitter and receiver, but it was pretty easy with the supplied tool. I think the receiver works from a bit farther away than the Chamberlain.I was disappointed with the beep feature because it starts beeping as soon as the door is opened. I don't think my family will appreciate the beep when I leave for work early in the morning. If Skylink (or Chamberlain) reads this, it would be really nice if the beep could be configured to start beeping after the door has been open for 5 minutes. The beep volume can be set to off, low, or high with a switch. It also has a mute feature which you can press if you know the garage door will be open for a while. When the garage door is closed, it automatically turns off the mute and goes back to normal operation. The Skylink uses a different kind of sensor than the Chamberlain that is mounted at the bottom of the door with supplied two sided sticky tape and has a pencil shaped sensor that senses the floor of the garage pressing up on the pencil shaped sensor. The sensors for both units work well and appear to be well designed.Overall both units work well. If the Skylink had a delay on the beep, I'd like it better, but I'll probably turn off the beep to keep from annoying my family and my dog. The Skylink can monitor up to 4 devices with a separate LED light for each, and a different beep pattern for each. Skylink has sensors that can monitor garage doors, motion sensors, water sensors, and other types of sensors.