Absolutely love my IPro. Haven't put it down since Saturday.
Guess it's a learning curve that most e-cig newbs must go thru. I started vaping with the lowly Njoy e-cigs from the gas station, then stepped up to a 510t kit>510mega>900mah eGo>1100mah eGo with LCD display. The difference between those toys, and this machine is simply night and day.
I bought 2 chargers along with 5 pairs of batteries thinking I would keep one charger at home, and the other at work. The charger at work is still in it's case. I leave home in the morning with a fresh pair of batteries in the PV and another set in my carry case. I really don't even need the spare batteries during the day, but what vaper would leave home without backups!
What I found most eye opening is with the IPro set to 3.7 volts vs a non regulated eGo bat measuring 3.7v, the IPro is able to run a 1.5ohm DC Carto MUCH better than the eGo battery can. I haven't yet bothered to measure both under load, but it's readily apparent that the IPro is able to deliver the wattage to the LR devices that the eGo battery simply can not. At around 4.5 volts, DC carto's rock.
As far as form factor, I do rather the size and feel of the eGo batteries. The IPro is a bit much in my top pocket. However, the difference in performance is so drastically better I'll just deal with it. Hey, maybe in a couple of years we'll have graphene batteries available that make mini e-cigs just as good.