As both the SVD2.0 and the P3 are both out, and I can only justify buying one new device, I think I'll go for the P3. Big price jump, but beats smoking, and a great device that makes me a happy vaper keeps me non-smoking.
As I have lots of 'backup' devices, I really do not need both, and with the P3, I can use any battery size I choose without having to buy another tube.