I skipped over the C3. Wore a C2 since 2005.
I feel the C3Pro is equal quality to my C2. Fit is similar. Really gotta love the pinlock over the stupid coating they used on the C2. Rode to work today (on my scooter) in nearly freezing temps, in the rain.. no fogging at all. (20 minute ride) No leakage from the top of the visor.
I have a Scala Rider G9, and they put the smoked visor actuator slider in the way... I'll have to accept a short mic boom as the unit will need to mount behind the slider. Maybe Scala will make a longer boom??
Mounting speakers is a joy, the liner snaps over oval shaped speaker slots. Easy to position, lots of room for the ears.
It's a lot quieter (on my scooter) than my BMW enduro helmet. And a lot warmer.
I only heard about issues with the C3.. but I am liking the Pro..