Very much this, your coil is what does the work, the tank simply tweaks and tunes what the coil has done. The tank matters of course, but point is make sure to choose the right coil for the tank, and make sure the tank has a coil for your needs. At 30w you're going to want something .5Ω to .8Ω IMO. I run a .5Ω coil on a 4.2v Aspire subΩ battery, it's very nice (according to Ohms law at max charge that's 35w, but realistically it's probably like 3.something volts so around 25-35w as I charge it full every night and only use it sparingly). When I had a .3Ω coil in there it was terrible, 1.5Ω and it basically did nothing. Gotta get the right coil for the right power.I think the tank does not matter as much as the coil. A lot of the more popular sub ohm tanks are making, and some times including, coils that are built for lower wattages. It works out well if you you decide to start using more power in the future.