So I got a Vboy Sx520, so far there are a couple of bugs with the firmware using 18650 probably due to the adapters the operating and charging voltage is .4v higher than the standby current (I don't have 2x700 to test on)couple minor glitches with the screen. As far as performance it's just like the sx500 but with a bit more power, true 222w (don't know why you would use that) 9.5v output and 120J in temperature control mode. Soft, standard, powerful, powerful+ and a power sxi curve as there is no way to manipulate the temperature as of now, although there's a loophole to use 222J it's not much use without being able to set a temp curve which it seems YiHi has resettle the J chips. I've tested it over a month, overall it's a solid mod in my opinion with the downside being the door and front materials, I understand why plastic in the front but it makes it feel cheep. Battery door is ok, you can move it like the q class door due to being magnetic but it's sturdy. 510 is solid, although I would had preferred better quality paint on the door atomizers can scratch it with the edges (Zeus) Overall I like the mod being a 18650/21700/20700, so once those 21700 become more widely available this mod won't be outdated. Performance on TC is solid, The constant power output of +\-5% can be seen on screen but I can't feel the difference, quite similar to the sx500 version but it has 3 boot menus, otherwise aside from NO lag when firing,(instant firing) it performs almost identical except the resistance sampling is far more stable in readings in the sx520 over sx500. It says in the manual personalized led lights yet I can't figure out if they mean the design or if I can switch it from white, no they can't shut off during operation. One big con is that the fire button is plastic and feels cheep also having it on the side is not as comfortable as sx500 in my opinion. What do you guys think of it?