the IMRs are great all around, but at 17670 and bigger sizes you are able to get ICR "standard" li-ion batteries that perform just as well given the same circumstances, but will last considerably longer. i'd suggest the AW ICR2600 or INR2900 from AW or Redilast. for vaping purposes pretty much any of the 18650s are high drain (enough), and with these li-ion 18650s you'll get a 40% increase in runtime over the IMRs, very solid performance, and high quality protection circuitry against overcharging, over-discharge, and other potential failure.