I picked up a C3 (with the SRC/Cardo unit) last week and put about 700 miles on it this weekend (both on and off road). I guess I've been a bit of a brand loyalist lately since my helmet rack currently holds a Multitec, RF-1100, and Hornet (I also had an RF-1000 a few years back). So, for me to go non-Shoei must say something for my initial impressions of the C3. As much as I love the Multi as my daily lid, the main driving factor for me was the integrated sunscreen... Just getting tired of lugging (and forgetting) sunglasses.
Overall, I am impressed with the C3.
Fit – Decent, but the RF1100 and Multi fit me a little better. Of course the C3 is still breaking in, and head shapes differ. You'll just have to find a local dealer or show to see if it works for you.
Ventilation – Good, slightly better than the Multi but doesn't come close to the RF-1100's ventilation.
Weight – Feels much lighter than the Multi, and similar to the RF-1100.
Noise level – Much quieter than the Multi, and a bit quieter than the RF-1100.
Field of vision – Much better than both the Multi and RF-1100. I also like the fact that the Pinlock extends nearly to the edge of the shield (similar to the RF-1100). You hardly notice the lines.
Form factor – The C3 is much smaller than both Shoeis. While this is probably an advantage over the Shoei while on the road, you do feel a bit more claustrophobic in the C3.
Gadgets - Like I said, I love the sun visor, but the "quick-release" chin latch makes strapping in and out, a single (gloved) hand operation.
Value – While the Multi will certainly win on price, I'd have to say the "value" of the C3 is pretty good, especially since I don't need to carry sunglasses anymore.
My big complaint would be with the SRC system. While I like the audio features: volume auto-adjust, speaker size, and slick integration (replaces the base curtain with a couple quick snaps), the microphone position and design drove me crazy. There simply isn't enough room between my mouth and chin guard for the thing to fit comfortably. I ended up bending the whole thing back and tucking it under the collar flap. I could still feel the flex cable sticking into my neck.
For anyone considering a flip, I would have to say that you'll want to at least try one of these on. I realize most places wouldn't let you take one on the road, but the noise levels, weight, and field of vision will probably impress you.
Knowing what I know now, I would still purchase the C3, however, I would have left the SRC in the display case (way too expensive for what it does, not to mention the mic issues I had).
Of course, if Shoei was to announce a Multi 2 with integrated visor, you'll see my C3 under the Classifieds section.
For those in the New England area, Moto Market in Acton, MA is now a Schuberth dealer and has all sizes in stock...
Of course, just don't expect the "deal" part of "dealer", but I think everyone is selling at list (for now).
Hope this helps.