I've been test driving a few BT headsets and I thought the results might be
helpful for others...

I bought my first headset about a year ago, a Cardo Scala 500, and still
have it. I made a good choice since it continues to work well, and better
than most of the others I've tried. It doesn't hold itself to the ear as
well as the others, but it sounds good and has a lever volume control that's
very easy to use.

These headsets were tested using a Motorola e815 phone.

Plantronics HS320 - this one was a little hard to pair with the phone. It
would also lose connection and I would have to turn off both the phone and
headset to get it connected again. It fit well on my ear and has a small
tip that channels the sound into the ear. This works well and without the
discomfort of ear gels that are like wearing an ear plug. The main button
for calling and hanging up is too stiff. I would have to push too hard to
sufficiently depress the button, and it was also necessary to hold the
button down too long before the headset responded. The same button is used
for changing the volume - you slide it forward or back. I didn't use it
much as it requires too much pressure to move. Audio quality was quite
good.

Plantronics HS 350 - this one uses the identical shell to the HS 320 and has
the same stiff button. It was easier to pair and comes with a usb charger
and car charger/cradle. It's more expensive than the HS 320, but the main
difference is the two chargers (the 320 comes with just a wall charger) as
far as I could tell.

Motorola H300 - I was intrigued by the fact that this one uses a AAA battery
and manages to get it into a pretty compact package. The obvious advantage
is no need to charge it and long talk time per battery compared with
rechargeables. I didn't use it long enough to wear out a battery as the
audio quality was not very good.

Motorola H500 - finally a headset I like as much as the Cardo Scala 500!
This one looks great and fits well on the ear (some reviews say the headset
feels loose, but it seems snug and secure to me). Pairing was a breeze and
audio quality is good (a little more bass than others). The main button is
easy to push and just a quick push is enough to activate the e815's voice
dialing. The buttons for increasing/decreasing the volume are small and
hard to feel/find when wearing the headset, but I don't find that I need to
change the volume much in normal use. Some folks have complained about
static, but I find it as clear as any other headset. I decided to keep this
one and use it along with the Cardo Scala 500.

When looking for a headset remember the variables, i.e. what phone you have,
your ear shape and hearing sensitivity, etc. I was able to check these out
by getting them locally and returning the ones that didn't work out without
penalty. I recommend that you test drive too, but hopefully some of this
information will be useful.