Just wanted to throw my two cents in as a regular user, not someone who is an experienced vapor or modder. I figure a lot of people that follow this thread like me wouldn't mind a basic users take on these things.
First off, Let me just say I am in love with these things. I've gone through 3 regular e2-r2s now and found the only time I've had leaking issues is when I accidentally drip directly into the cup. I don't have any mods yet, so all I've used this on is an eGo. I just pat it down on a paper towel and they are good to go. With protected batteries it really hasn't been that big of an issue for me. I tried PTBing a couple but I always end up doing it wrong and stuffing the ptb too far down into the cup. I'm sure with a little practice I'll get it, but I have shaky hands and the tweezers I use are too big.
First off, let me just say vaping these on a 3.7 tends to get a little harsh. The vapor is very warm, almost close to burnt. I just bought a little sister from someone in classifieds, and I can imagine these things been great at anything lower 3.7. I'm very eager to try it out. But really thats the only bad thing I have to say about them so far.
Whether you drip, use atty/carts, or even regular cartos nothing below 5v is going to come close to the vapor production and taste I get out of these. Even with all the problems mentioned in this thread I don't think I'll ever go back to using attys or filler cartos. When you get one that works perfectly nothing compares convenience or taste wise.
I just wanted to thank everyone who is doing their part to make these things better. You guys are really unsung heroes of the vaping community. These things have gone a long way to keeping me from dragging on another analog and I look forward to the e2s getting better and better.
If you have been browsing this thread and are just starting out like me, I would really recommend these to anyone. There is a bit of hassle getting things just right, but its well worth it in the long run. Anyways, just my two cents. Keep up the good work guys.