all i can say about campag stuff... look at how much cogsets cost.
shimano, or sram stuff does not cost as much.
$150 chorus cogsets...
i've never seen, much less tried this thing:
http://jtekengineering.com/shiftmate_straight.htm
I'm a bit curious.
being that you could, theoretically...
use a Campag ergo shifter, which i do like, however i want the new SRAM Red groupo, and get away from that mouse ear, i'm sick and tired of it for sprints... the SRAM stuff is much better... (wrong tangent)
but if you're bent on using campy shifters...
perhaps you could use an X9 or X.O rear derailleur
and an XT cogset... you pick it... they make 34-11t cogsets
i have a Hunter 29er that i run all SRAM, and ride the bike for everything... the X.O groupo is awesome. IMO the X.O is better than Record. it shifts nice all the time, and you have a ton of MTB cogsets to choose from.
i really do not like $50 chains, and $150 cogsets... but obviously i buy them, along with Sidi Ergo2's
thats my 2cents