Bluetooth: Jabra BT2040, Jabra VBT185Z, Plantronics Explorer 360 with Belkin USB dongle
Logitech Clearchat Pro Wireless USB (comes with headset and dongle.)

My purpose was to get a wireless set which would allow me to record prompts, interact with my dialog manager, and experiment several hours a day creating models while being able to walk around the room and do other things. The result overall is that all of them work equally well allowing me to achieve close to 100% recognition accuracy after a non-trivial setup process on my Linux box. But they have subtle differences.

The Logitech is a comfortable wear, with padded earpieces, nice quality sound coming in, easy control of mike on and off with a big button, no volume control on the headset, most difficult to wear if you are in a cool room and wear a hoodie at the same time. This unit is relatively expensive, MSRP in Canada is about $130, I got mine on sale at about $80. Unless you are looking for the nicer sound and comfy padded headsets it does not give any advantage over bluetooth except for:
- I did not notice any crackling on this unit, but I did on all the BT sets from time to time.
- It does have a hum/hiss of its own quite different from the BT sets, which might give some advantage
It does not have a noise cancelling mike, which normally would come in that price range.

The bluetooth sets:
They are all equally uncomfortable to wear for an extended period stuffed into your ear. However they work surprisingly well. The J2040 was $13, the J185 $15 and the Explorer $30. The Plantronics seems to be the most robustly built, the Plantronics and the J185 have tiny buttons for volume control which I could not use once it was in my ear. Sound quality is quite good, but used with Festival TTS there were times when I could not make out clearly individual words which might have been clearer through a quality speaker.

My favourite is the Jabra 2040. It has no volume controls on the unit but that is irrelevant to me. It is the cheapest and the quality is fair. The big advantage is that it has a replaceable battery (AAAA type). This is really good when you are working away and the batt voltage disappears suddenly. Swap out the battery for a new one and you are on your way again with minor inconvenience. The others (including the Logitech) take about 2 hours to recharge which is a pain if you are on a roll. AAAA (four As) batteries can be hard to find. There is some advice on the Internet regarding using the component batteries of some rechargeable 9V batteries. I dismantled one of these and now have a stack of rechargeable batteries which can be swapped out in less than a minute. This process is not recommended for situations where the headset can be knocked about since the batteries are slightly smaller than the battery compartment which gives it room to move.

When I get errors with wireless sets they tend to be the words ZERO, ONE, LIMA and SYSTEM. These are the words that pop up in my dialog manager diagnostics most frequently. Sometimes when I pronounce these words Julius thinks I am saying something else, but what Julius hears is different each time. This seems to say that the word enunciated is interfered with by cracks, pops, ticks, missing packets but quite randomly, otherwise Julius would hear the same thing each time. This makes it hard to have the dialog manager flag a possible error when a particular word is heard.