For many years I have used Autocom units and have owned 3 of these over the years. Having got to the stage of needing replacement I went for the Scala set because of the bluetooth - no wire facility. The first problem I found was that it would not pair with my garmin nuvi 765T. The garmin pairs with my mobile phone and my mobile will pair with the Scala, but Garmin to Scala , no! It turns out that there are only certain Garmin models that will pair so if I want Bluetooth I must buy another Garmin at around £300!
The next problem was the headphones. The positioning has to very exact to hear properly at any speeds above 50 mph and the performance is not as good as the my Autocoms systems were. The fact that the headphones have to be right up resting on your ears to get them to work reasonably means that they are slightly uncomfortable, you have a hard bit of plastic always pressing on your ears. The instruction on the internet and in the manuel are at odds with each other. One says have the mic in front of your mouth and the other at the corner of your mouth. The position of the microphone is also not clear the text says it must be vertical yet all the pictures show it to be horizontal. Also the front of the mic that needs to be to your mouth is only marked by a small bit of yellow tape that falls off as soon as you take it out of the box and you have no way of knowing which way the mic should be. Because of the lack of Garmin/system Bluetooth I have had to use a wired connection which is normally for an MP3 player. This is a problem because the MP3 system is the lowest priority, so if you want to hear the Garmin instructions neither rider or passenger can utter a sound, not the best situation when you are trying to find somewhere.
The one big advantage is the lack of wires to get tangled up getting on and off the bike and the fact you can talk to your passenger when they are off the bike and within about 50m of you.