Droid Turbo 2 charger charged the Pixen in decent time.

[hal1]

My Pixel charged from 38% to 100% in 1 hour and 20 minutes with the charger from my Turbo 2 and an Aukey adapter.. Not really sure how this compares, but it's fast enough for me - assuming it's safe. If interested, check back tomorrow this time and I'll see how far it gets in 15 minutes when starting at 10%

 

[dpham00]

You can use battery monitor widget or similar to measure battery charging rate. I would guess that it is doing 5v/2 or 2.4a.