Exactly: P3P is worth only if you really need 4k.I was thinking of getting the P3A since I really only wanted to shoot 1080 and liked the 1080-60 that my old GoPro used to shoot on my P2. But I went ahead and bought the P3P for the hell of it.
For the first couple of months (other than a sample to see it worked) I just shot 1080-60 but then I decided to try 4k and really loved it. My computer can edit it fine (not fast, renders at 0.1x) and the result is superior. Then we got a couple of 4k TVs at work, 65" and 70" and WOW - amazing. I am so glad I went with the P3P - worth the extra for me. 2.7k works nicely on P3P now and looks good on my 2.5k monitor. But nowadays I shoot 4k for everything except long distance flights. Even my phone shoots gorgeous 4k - things have progressed a lot. I probably have to spring for a real 4k monitor for working on these files eventually but haven't done it yet.
Otherwise:
- picture resolution is the same;
- P3A has 2.7k so you'll still have the chance to crop and zoom (not as much as P3P but still...);
- it's difficult to perceive the limited bandwidth of the P3A under sunlight;
- reamember 4k videos needs huge amount of memory to store them (I ended keeping the lo res videos saved by th Pilot/Go app)
- editing 4k videos need time and powerful pc
Reamember that once you'll buy your P3 (whatever the flavour) you'll soon spend extra money to buy (at least) one extra battery and a backpack (or hard case): don't forget to involve your wallet in the choice .
Personally, I went for the P3A and I am VERY happy with it.