I love mine.. I have 2 901's (1 white / 1 black) and 2 4081's (1 white / 1 black). I tend to find myself using the black 4081 all the time. I'm also having really good experience with battery life. I have a 2 hour roundtrip commute to work, then 6-7 hour workday, and 1 battery lasts me the entire time. Throw the 2nd one on for home use, but I find that my commute to/from work is where I do the most vaping. I do have a 510 on order, based on all the good reviews I've seen on it, but I'm sure I'll still throw the 4081 in my pocket on a night out on the town.
I don't drip however. I keep a small baggy with me with a couple of filled carts, never counted how many puffs I get off of a cart, but I use about 4 filled carts per day. Carts aren't that difficult to fill, I pull 4 empty ones out at the beginning of the day, line'em up in a row, fill'em up, put in the plug, throw'em in the baggy. 5 minutes total time for the day, and I'm good all day.
My 901's are basically just backups. I got them after reading how great they were on here, but honestly I can get just as much vaper production out of the 4081. The only plus I see on the 901 side is that the carts seem to last a little longer.