I've been using a crown 2 tank for the last few months and I love it. I rarely run into one of those coils that burns out after a day. I almost exclusively use the .25 SUS 316 coils. I'm concerned because I just found out that they have nickel legs and I use them in variable wattage mode (typically 75W). I read online that nickel can be dangerous when used in variable wattage mode. What do you think?