Glad to see this one's still going...
If the wheels were just for racing or anywhere else where support was assured, I don't think there would be any question for me - the Ultimates would be the only choice of the current crop offered to the public. If the sponsorship also offered the new classics tub, the wider/rounder one Van Summeren used for his P-R win and that the guy who 'won' the P-R Challenge last year also rode, then I'd probably take that for non-mountain days.
With regards to the Cosmic 80's, a team I'm friendly with had these wheels added to their fleet for a high-profile race, with the expectation that they would be ridden by all team members to support the Mavic sponsorship. Not one rider at that race was interested in using those over their standard Ksyriums - the feeling was that they felt 'dead' and were quite slow for anything but a TT.
Finally, in response to the ideas of running a 25c tire on a Cosmic or that the Cosmic is just an Open Pro rim with a fairing, I can say that this is most definitely not the case. As said, the Cosmic family with their 13mm internal rim width is much narrower then an Open Pro and really just about any other rim out there. That means that using a 25c tire might get you back to the ride feel of a 23c, but has done so at the expense of another 25-50g per wheel of rotational weight - to say nothing of what's it's done to the already poor aerodynamics of this wheel.
I understand it's not too bad when a 19-21c tire is mounted (and I do recognize that the CC80 is a decent wheel for aerodynamics), but as you can see, with a 23c tire, you're paying a weight penalty for the depth, without really achieving any advantage.
Mavic wheels will always have fans, as they do feel very connected and responsive, but I guess I've always felt that once you've done your research, it's pretty easy to find other options out there that provide the same connection, with greatly improved performance across the balances of ride quality vs. aerodynamics vs. weight (vs. price too!)