I've been running the P3 at 10W, mostly on 18650s.
I'd rate the batteries as running best with a VTC5, followed by VTC4's and then AW. I'm seeing about 13-15 hours on an AW to a bit over a day with the VTCs. (this is considering sleep.) I didn't run my 2.5 in 18650 mode so can't really comment there.
18350's have been a bit of a headache. 2-3 hours, compared to 4-5 with the 2.5. I've found that I put the mod down showing ~25% battery, pick it up, and it won't vape, showing empty, and the LED begins flashing. I re-seat the end-cap and it'll go back to 25%+ and vape again for a bit, at least long enough to get to a spare battery. Honestly, this is a bit of a deal-killer for me as there's no warning between normal and dead.
Don't have a complaint with the functionality using 18650s other than size. It's quite a bit less pocket friendly.