Sure I'll chime in! I love both of these boxes. I've been testing 3.7 & 5v using all of my juices and a 2.6ohm atty. I'm finding that some of them are best at 3.7 and some are better at 5v using the same atty. A 2.6ohm atty on 5v is producing a lot of heat and can burn some juices while bringing others alive, it's amazing, you just have to experiment. As for cartos I prefer the 2.8-3.0 ohm carto on 5v, it seems to be the sweet spot for most of my juices. I also use either the 1.25's or 2.0ohm duals on the 3.7 for an almost equivalent hit. More on this later, I gotta go eat breakfast!