I have a Kamry mech mod which is bottom fire / hardware switch. Sadly, I have very crappy over-protection batteries at the moment, but that will soon be resolved with new Sony US18650VTC5s. I do not use a kicker or other power / current limiting as that is the job of a well built coil (and my crappy batteries for now). Otherwise, I have only used Ego style batteries (side-fire) in the past and honestly, I don't have a preference. I think it's nice for variety (and to give your hand a break) to have a couple of different options. My IPV2 has a side fire button and a top fire sensor, so when I get my batteries, that single box will give me two different firing options. Variety is the spice of life! =)