I've spent the last 4 months trying different combinations of cartos, atomizers & variable voltage. Specifically I tried an expert 510 atomizer, 901 atomizers, every kind of KR808-D1 cartomizers I could find & for a short lived while variable voltage thanks to a terminator from notcigs.
Expert 510 atomizer = Good vapor, but little flavor
901 atomizer = Decent vapor & awful taste
V4L WOW Vapor & Premium Cool Carts, Vapornine Turbos, CE2R3 from COV & Old school 808 cartos from altsmoke (who must still be trying to get rid of old stock as they were the same 808 cartos I remember 1st trying in 02/2010) = All failed on one level or another.
Those same cartos with a Terminator = Great warmth, flavor & vapor production. However, the Terminator that I got was not well glued together & I'm waiting to see if I'll get a 2nd replacement or try to fix it myself.
The best I was able to find was Low Resistance KR808-D1 cartomizers from litecigusa.net. You get the pro's of using a variable voltage
device without the hassle IMHO.