I have no clue, other than my Silo Lite (which uses the same aspire BVC coils as the Vivi Nova) they are my favorite go-to tanks. I even prefer them over the Mini Nautilus.
I vape 80/20 pg/vg, and with rare exceptions I don't vape any dark/thick liquids. I stick mainly to light colored menthol/minty flavors, with an occasional fruit flavor. I usually get 10 days or so per each coil in the Vivi's. ( I don't know how many ml's, I don't keep track of fills, but I vape all day long, even at work, so I go through quite a bit in 10 days time)
On the subject of the GS Air trouble, I still have not had time to mess with them. I had to make an unfortunate trip to the vet today and say goodbye to one of our dogs (not the one in my avatar). He was my buddy for 11 years, so I'm a little bummed and don't feel like playing with vape gear right now...