I finally broke down and bought some new heads for my Nautilus when the BVC heads hit the local B&M. I bought 1.8 ohm because I tend to vape lower voltages on the Nautilus due to the warmth of the vapor. The BVC hits really well, maybe better than the original coils when the quality was excellent. Time will tell, but everyone is saying that they are getting more than a week, sometimes two before the flavor falls off.
It's funny how coil wicking efficiency determines the voltage you vape at. Sometimes, I vape my Kayfun with the same 1.6 ohm coil at 3.4v. Other times when I change the wick I can vape at 3.7v because that particular wick is better at keeping the juice in the coil without gurgling. Seems like the sweet spot is not always easy to get. Wick length, snugness in the coil, whether it's twisted or not, and how the ends are arranged in the juice channel area all make a difference.
I'm amazed when I get a box of Kanger or Aspire heads and all 5 are excellent. There's frequently some variance from head to head.