I've gone through a handful (6-7?) of them over the past 18 months, mostly because I dropped two of them, same day while out golfing, on the paved path, on back to back holes, I was miffed, another two of them just plain stopped working, tried swapping coils, still a no-go. If you hot water rinse the coils out when it's time/juice gets dark, they last a decent amount of time (let them dry for about 12-24 hours), I can run anywhere from 20-30ml of juice through them before replacing which is pretty reasonable for the price.
I have yet to try the Nautilus BVC, so I couldn't give you a fair comparison, but they hold their own against a protank 2. I also use a 510-ego adapter, on my ego batts and MVP to loosen the air flow with the T2.
Just to add: When you rinse the coils, just give a little tug on the wick, slowly, to be able to rinse out the "contact" area of the wick and coil, it helps lengthen the life of it.