Like you I took the natural progression through pvs - joy 510, Ego then added the EgoTank but wanted something with more battery life and options. I researched variable voltage devices read up, compared pricing etc. I decided on the Infinity because it was slim (I didn't want a big fat mod), shiny and easy to use. Turn the wheel to the voltage you want and vape, no complications, turn it up, turn it down, find your spot for any juice. I later invested in the BuzzPro, operates the same as my Infinity a little fatter, a nice purple color, dial the wheel up or down, vape. Both have treated me well, I love them. I can Vape any juice at any voltage that *I* desire Both range from 3.7 ish - 5.6 ish volts.
I only need to change batteries once a day, less if I have swapped mods during the day. I use cartos, tanks w/ cartos and sometimes drip. I can use most any size carto/atty but using a small adapter,so it's versatile.
Do you want variable voltage... you will not know how much you want it until you try it, or why you didn't try it sooner. Wouldn't trade mine and I'm glad of the company I went with, dependable, active in the forum so questions are answered fast, he stands behind his work.