Have to say that I have the i2 charger and it's pretty great. That being said, if I could do it over I would have purchased the i4 from the start. It is only a few dollars more, has two more bays, and if you only want to use two at a time, will charge them 50% faster than the i2 (750ma vs 500ma charging amperage). I know there are also 1a chargers out there but that is not something I have messed with yet.