I had a 510 for a few years, after not being happy with an older Motorola unit. When I accidentally ran over it, I thought I would buy a Voyager Pro - a little sleeker and a better noise reduction.  After receiving two defective Voyager Pros, I went back and ordered my old standby Voyager 510.  It may not be as sleek as the Pro, but it works like a champ and I don't get any complaints about background noise when driving.  (Yes you still need to turn down the music though)