Originally tried Motorola HS820 with my Motorola E815 phone. Was happy with it at first. I liked the way it fit on my ear and it was easy to use. However, everytime I used it, the person on the other end would complain about hearing an echo. I tried turning the volume on the handset and headset down, but could not make it go away. I finally concluded that it would be useless if the person I was talking to couldn't tolerated the echo.I read reviews on many different headsets, but most of them had complaints about 'echos'. I really wanted to get a Motorola headset so the chargers for my phone and headset would be compatible. However, based on the reviews I read, I gave up on the Motorolas and tried the Plantronics 510.I've had my 510 for about a month now and am very happy with it. The sound quality is great. I don't believe the person on the other end knows if I'm talking on the handset or headset. I've had a couple complaints of an echo when I was talking to someone who normally speaks fairly loud. I had the headset volume louder than it needed to be. Once I turned to volume down a tad, they said the echo went away. This headset is definitely louder than the Motorola - probably because of the way the earbud fits in your ear (which is probably why the echo isn't a problem - the sound from the earbud doesn't reach the microphone). I still prefer the way the Motorola fit on my ear and the way the buttons felt. The buttons on the 510 aren't as easy to use, but they are tolerable. In the end, the sound quality is probably most important and the 510's is great.