I have the C3 (just looking to apply the fix mentioned for the visor dropping)
Planning to keep it as I have the C3 integrated system which is now about 2 years old.
I believe that is the same SRC/Scala system but built to fit the C3 helmet.
In my view it is very good, the speakers mount fine in the C3 helmet recess each side and the replacement collar is slightly tricky to fit but easy to operate.
Use it pairing with my Zumo which acts between the Helmet and iphone - all works OK.
Not used the intercom yet for bike to bike stuff.
The battery has lasted well so far, the FM radio is OK but reception is not the best I assume due to the aerial arrangement.
Purchased it from a seller on ebay Italy who offered the best price.
Hope that helps.