Kat,
I ordered two of the Smowell DPV-50s---one from fasttech (for $39 pre-ordered a month and a half ago) and another more recently from gearbest when the price dropped to $32 bucks. The one from fasttech arrived on Saturday. It was DOA. The chip was defective and the display screen showed only gobbledygook (randomly changing pixels, like a kaleidoscope).
I'm not unhappy that it was defective, however. Construction seemed shoddy, and I had concerns about the chip anyway, since it's the same chip that had problems in the SMOK 50W box, the one they replaced immediately with the 65W version. I've even wondered about the possibility that SMOK dumped all those 50W chips dirt cheap to Smowell.
At any rate, now I'll get my $39 back from fasttech. Presuming that the second DPV-50 is not defective when it arrives from gearbest, I'll decide then whether it's worth keeping.
I have about 30 of the earlier BVC coil heads, in both Nautilus and clearo style (for the Aspire K1 and CE5S). While the kerfuffle over Aspire's use of "ceramic" (fiberglass?) in those heads warrants concern, my experience is that those coil heads perform brilliantly---giving great flavor and a lovely, smooth draw. I've decided to use up all my stock of the old heads, but to do so more quickly than I otherwise might, vaping each one about half as long as I would have, then tossing them.
I rebuild my Kanger Subtank and Atlantis heads with 26 gauge vertical coils at about 0.7 ohm wicked with KGD cotton, and they perform just like the originals, but the smaller BVC Nauti and tiny BVC clearo heads proved too hard and finicky to rebuild effectively for me, so I gave up on even trying to do so. Once my stock of old heads is used up, I don't know if I'll buy new cotton-only heads for those older Aspire clearos (Nauti, K1, CE5S) or just retire them in favor of RTAs/RDAs.