I've got CO2s for my freeride board. Great response/stiffness, but I think they're way overpriced (I scored mine cheap on Brociety last year). The Rome 390's will be too soft, I'd say look at the Targas instead. I'd also look at the Ride SPi or Double Agent.
The targas look pretty sick anyone know what the high backs like? Are the Co2's as light as burton goes on and on about?