I have the V2, (which you have pictured), and a knock off XL3 mini,
XL3 Mini Variable Voltage - Black Rubberized, that I have as backups for my other APV's. They do work well when equipped with the right atty's or clearo's. The only problem I have had is with the V2 eGo, it will fire in your pocket if you forget to turn the head off. Other than that, it works well. Joyetech has corrected that problem with the button as it is now flush to the head. They do have a V3 head available at a few places now also,
Joyetech eGo T Upgrade Flat MOD Controller.... For the prices of all these, they do make good backups to a collection....