We've been down this road many times for clients using Axxess systems. Recently we went with a large deployment of GN (now Jabra) GN9350's. The issues we've found are:
1. When used over the ear as opposed to using the large head wrap, the unit is very uncomfortable after the first hour or so and many people go back to using the handset.
2. Batteries tend to go out with no warning and do so frequently.
3. The units tend to go into la-la land at times and require a reset procedure that you'll want to have well documented so you can explain to users how to fix while talking to them on the phone.
4. VOLUME!!! or lack thereof! Your users that are wearing the headsets can be heard very well, but it is often very hard to hear people on the other end, especially if it's a female. They will need to turn up the volume on the Axxess phone to max each time they take a call, and make sure the volume on the headset is all the way up. What makes this worse, is that the unit doesn't make a nice acoustic seal at the user's ear, so outside A/C noise etc. adds to the issue. We'd love to find a good unit that has the ear plug that inserts into the ear canal to combat this.
Plantronics is pretty much a staple and it will work to average expectations. Nothing better (or worse.)
Although I haven't used them yet, our next test deployment will most likely be with Sennheiser:
https://www.sennheiserusa.com/private_headsets_office_wireless We prefer to stay away from Bluetooth for several reasons when possible but if everything else was a plus, we'd overlook that issue.
There are also some newer units using the DECT 6.0 which would be very nice. If you find a good unit using this technology you may want to give it extra consideration.
Whatever product you try, please post back or shoot me a PM and let me know your thoughts as this has been a heavily discussed topic here in the tech and private forums.
