Im in the same boat as you, have a nautilus, 11 watts was fine at first but ive been vaping a couple months now & i have my mvp2 cranked up to 11 and its just not warm like i want. Its actually kinda cold.. nautilus with bvc can easily handle 15 -20 watts right? The 1.8 ohm coils say 3-6v where the 1.6's say 3-5. I have a pack of 1.6 & 1.8, i deffinetly preffer the 1.8, they seems to give more vapor / perform better. I think im going to get a ipv2, the one im looking at is the revised version. So its better then the original. It has a spring 510 or floating pin instead of one you have to adjust with screwdriver like the o.g, also has beefier hex screws on back so they wont strip like og, has better buttons i guess, ribbon for battery and other fixes. I'll be able to actually get a nice warm vape with nauty like 15-20w, can get a atlantis and even get a rda or rta and learn that. Istick is nice little device but its not true 20 w thats why i decided against it, you can still get like 16 or 17 watts max with nautilus , cheap to, $50, the revised ipv2 im lookin at is 100, with free 30 ml juice though