I have three new batteries, the one high capacity (5870mahr) battery that came with the
P4P and two of the standard 5350mahr batteries. I thought it might be difficult getting the new batteries and I needed more batteries for a trip I plan to take in the next week or so and I purchased the two standard batteries as backup.
I have flown three flight with the 5870 battery getting an average of just over 20 minutes with my last flight at just over 22 minutes while landing at about 27%. The standard batteries have given me an average just under 18 minutes with a high of 18.6 minutes while landing at about 27%.
So, call it 2+ minutes longer flights to 27% or so but if you were to push it or need to push it the max flight time would likely be closer to 2.8 minutes longer -- useful if you go out too far.
Brian