I've had a few of the Cig2O offerings, but largely have had a similar experience to you. If I were in the state of a strong nic-fit, the 8mg cartomizers can do the trick to cut some of the fiending, but it certainly does no good in acting as a realistic substitute (especially in a bar). At best it can only delay that damn impulse to light up, but I keep it handy in case I can't sneak away to an outside location for a long period of time.
But, at least in my case, I think it's psychological mostly. I'm back to almost a pack-a-day myself and I noticed pretty much the exact same amount of 'relief' from 8mg to 24mg cartomizers. Doesn't displace the feel and action involved with the cigs.
I think, insofar as a quitting device is concerned, that an e-cig may be helpful in raising the bottom end threshold of when the urge to light up starts to make you go bonkers. Maybe even reduce how bad the 'going bonkers' goes.