I come to the opposite conclusion. I like my Solo II far more than my IQ. The IQ used to be my favorite. But, other than the ability to switch batteries and concealability (Something I care nothing about.), the Solo wins for me in all categories. Tube, heater; that's it. The IQ is all kinds of finiky and why you might not be having as much up-time with it as you'd like. I tend towards being careful and being (reasonably) clean and the IQ has always worked. But, I can certainly see how any of a number of little things can go wrong with the IQ that would cause it to not work. Reliability should certainly be a factor in any vape purchase.I own a davinci and a solo 2. Love my Davinci. When it works. Right now it does not work. It IMHO is superior to the Solo 2 in almost every other way. But the area it is not superior is significant - Battery life. Shit I dont even know where my Solo 2 charger is because I so rarely have to charge it. Its an absolute beast. When My Davinci works, I get maybe 3 sessions then it needs to charge.