I have now tried the .5 ohm and the 1.2 ohm OCC coils. They both leak, have muted flavor, and they both suffer from severe spitback. However,the RBA coils suffer from none of the above and have much better flavor. I just ordered 4 RBAs to have some prebuilt spares on hand. Finally, I have found a tank to replace my Kayfun v4s. Although the flavor of the subtanks is not quite as good as the v4, their versatility easily replaces my v4s as my all day tanks. I had to find a replacement for my v4s since they are too unreliable to use with temperature control.