i've used plantronics backbeat for just over a year. i have a gigantic head, wear glasses/sunglasses, and my ears off uneven (yeah, i know, i'm the picture of beauty!) and the headset fits and is comfortable (sometimes i forget i'm wearing it, thus looking like a douche who walks around with his bluetooth on at all times, trying to look important).
the sound is GREAT. i'm a music snob, and i'm pleased with the sound.
the problem:
it worked great on my old blackberries, but has been pure poo-poo on my epic ever since rooting and installing custom roms. it usually pairs, sometimes connects, mostly disconnects randomly, and most of the controls don't work. and when they do work, they work for every possible app (so i can't just start and stop music. nooooo, pressing play on the headset starts music, radio, video, and podcasts.) i'm HOPING that the official 2.2 will fix this, but if it doesn't, i will be officially reclassifying this headset as utter garbage. it would be a pity too- because i REALLY love it when it works.