I went ahead with replacing my old cardo intercom with the sena AGV ark.
The reasons for replacement of the very old model cardo is that it had a boom mike that always got in the way and stuck on the side of the helmet as an obvious afterthought.
The AGV ark is supposedly only compatible with specific AGV helmets. Since I had no intention of replacing my Nexx carbon helmet I chose the helmet fitting that seemed to be nearest to the profile of my Nexx helmet. As you can see it was a good fit. Since I intended to use Sike 291 to bond to the helmet which has gap filling ability I knew I could work it out anyway. The ark fitting has the disclaimer that if it wrecks the finish on the helmet if removed using the adhesive they supply they don't accept responsibility. So I'm glad I chose Sika as it can be removed without damaging the helmet.[You must be registered and logged in to see this image.]
I chose the AGV ark because it doesn't look out of place on the helmet, has a mike that sticks onto the inside of full face helmet, has an optional handlebar control meaning not having to take my hand off and grope around on the side of the helmet while riding and is current state of the art for intercoms.
Since my GRiSO is set up as a long distance tourer the Garmin GPS and an intercom are necessary.[You must be registered and logged in to see this image.]