I have been using one for a week or so - no leaks but one, when I deliberately turned the fill control to "on" to see the leaking. Very pleased - 2 minor cons:
- I use flat drip tips (Atmizoo Ray), so when I occasionally rotate the tip to adjust for grip, I twist counter clockwise to insure I don't open the fill control.
- Great flavor, but my 4 mils of juice disappear at an astounding rate. More capacity would be great.