For intensive use I'd recommend against use of headsets.

We've found the Jabra Speak 410 (USB) and Jabra 510 (Bluetooth) speakerphones to be much more comfortable and microphone and noise cancelling are excellent.

IMO speakerphones are much more natural to use than headsets for a daily use.

Jabra 410: http://www.jabra.com/business/speakerphones/jabra-speak-seri...

Jabra 510: http://www.jabra.com/business/speakerphones/jabra-speak-seri...