Wow! Thanks for the replies! Everything you are all saying is confirming my experiences.
I should disclose I use a ProVari V2 with a full size Nautilus. My girlfriend uses a ProVari Mini with a Mini Nautilus. We were extremely disappointed with the BDCs.
When I am using ProVape juice, I easily get through a 30Ml bottle and just toss it because I am going to clean tank and change flavors anyways. After using BDC's, I am quite happy getting a 30Ml bottle through a BVC.
On the other hand, something like Johnson Creeks Silverthorn (extremely flavorful, dark and cloudy), I can barely make it through a tank (5-6Ml).
Thanks again and Happy New Year!