I don't have anything to offer about the TFV, I don't have one. On the RX200, aside from the charging issue, a topper with a too-long 510 connector-- I have read 4.6mm or greater but I don't know that-- can cause the machine to "lose" the atty. It will say "No Atomizer" despite it being right there on top, plain as day. You have to unscrew it and tighten it back down to get it to pick up again, which can be annoying. It doesn't do it with every tank, just some of them. Mine-- I have 2 RXs-- will do it with my Indulgence MT tank, and not with my Advken Ωega. The problem is the 510 connector is not as good as it might be. The connector can be replaced with a quality 510, like a Fat Daddy Vapes, for a few dollars with basic tools and some skill.Photos and a description of the process
here. The HG2 batteries ought to last all day, and then some. Mine do.