Got the Dragonfly, very pleased with it. It's a wonderful little DAC.
A few quick thoughts, the Pandora's PCM1773 DAC doesn't seem to be quite as good as the ES9018 in the Dragonfly (which is to be expected considering the massive price difference between the chips), but they're very close. The Dragonfly has a bit more texture and edge in comparison to the Pandora. Neither have any noticeable hiss or interference. The Pandora is only capable of 16/44.1 whereas the Dragonfly can do 24/96. This doesn't really matter since most of my music is 16/44.1 to begin with, but it should still be noted.
The amps however appear to be on the same level. Both are strong and don't color the sound, and while the Dragonfly does have a little more power than the Pandora's amp, they're not very far apart. Personally I think the Pandora is the better one in this regard because the amp stage of the device is pure analog instead of digital (in other words, the volume isn't controlled digitally).
The Dragonfly doesn't work directly from the USB HOST port on the Pandora because it's a USB 1.1 device, which requires the use of either a USB hub or USB-OTG. I'm gonna pick up an OTG cable as soon as possible.
Also something to note, the 1GHz Pandora has had a $100 price drop. More should come in the future, too.