The earpieces come with multiple foam ear tips, and you can get replacements very easily which mean that I just swap them every use, but the reality is that I am using them with the same few refs most weeks so I just label the earpieces and they use the same ones. I also clean them with anti bacterial wipes after every use too, just incase there is any sweat on the wires etc.
They a bit prices at the minute, but that is for 4 units, a normal referee would probably only need the 3 set which is £530, which is not much more than a new set of Touchline's or Ervocom's. In the next few years the technology will decrease in cost and so will the prices, as this happens and they become more affordable I'm certain that they will become much more common, and will hopefully be embraced by the FA at lower levels.
On a side note, does anyone know if there are rules set regarding when and where they can be used?