Well, I've only had mine for about a month now. These were my introduction to RBA's and of course there can be quite a learning curve involved and I'm still in the learning process. At first I was only getting incredible vapor production and only so-so flavor from them. Then I tried a pre-rolled stainless wick from Vapor Kings and I was in business with vapor and flavor.
However, that only lasted for a few days. The resistance of my coils would change as much as 1 ohm, and the performance of both AGA's became very inconsistant. I haven't had the time to wrap new coils as I suspect they have a short or hot spot in the current coils.
I still prefer my cartotanks because of their familiarity and consistancy, but the potential of the AGA's are very promising.