If dji used the same batteries in both quads everything would be better for everyone.But...if someone has both quads   
has a collection of batteries...Enjoy flying

Why would it be better for everyone ?
P2 owners use P2 batteries, P3 owners use P3 batteries, if you have enough spare cash for both then you can afford some more batteries

johnwarr@live.c Posted at 2015-7-17 05:18
Why would it be better for everyone ?
P2 owners use P2 batteries, P3 owners use P3 batteries, if you ...

To imply that because you 'can' afford to buy the P3 if you already have a P2 somehow means you can 'afford' the new batteries as well is ludicrous.  I can't afford the P3 and the main reason is the batteries.  I can't see any possible gain if I can't achieve the same flight time I currently enjoy.  I can have the P3 here tomorrow - with one battery, maybe two.  What does that do for me when I currently enjoy more than an hour of flight time?

The P2 was using 3s packs DJI wanted to improve its product with the P3 and use 4s