I have had my GTl for about six months and enjoy the bike.
The BMW comm system is the only available choice to work with the factory system and the Schuberth helmet. The speakers are horrible distorting music and sound. The dealer Eurocycle of Tampa Bay has been great and swapped them out for another pair with no improvement. They caled BMW with no response and I have called and left messages with no response. The dealer had several people listen to both sets and all admitted the sound quality was miserable.
I can not replace them with another brand. I had used the Nolan helmet and speakers before the BMW system was available and the sound quality was fine.
I would go back but the Nolan has only limited capability with the GTL.