pkcpga
1000+ Head-Fier
I wouldn't argue that Mojo is a much more capable, and better sounding, product than either DragonFly (I have the Red as well as a Mojo) ... but that level of exaggeration does no one any good.
Mojo is, physically 8 times the weight and 10 times the size of the DragonFly units (with the cap on, the DragonFly is the same length as the Mojo is wide, for example).
As for battery ... at least when traveling, you either carry some way to charge the Mojo on the go (which, if you're flying, means a portable battery that's going to be at least the size of the Mojo itself in order to actually be useful, or you gamble on in-seat power), or you're done in about 8 hours. I can easily get longer than that with just my iPhone 6S and the DragonFly.
Here's the specs
Df 12mm X 19mm X 62mm cap removed from audioquest site weight 69g
Mojo 80mm X 60mm X 20mm from chord site weight 180g
So about 2.5 times the weight and about 3.5 times the size. Far cry from your estimate.
My df with iPhone 6plus did not last more than 6 hours with using the onkyo player app, so I'd need to charge my phone battery at that point, phone battery at less than 20% in power save mode.
This way my phone battery will be at 30% after 9.5 hours of use and I'd have to recharge the mojo but it lasts me 9.5 hours. Specs state 10 hours but I received about 9.5. The only way you'd receive less is if the first charge you didn't leave charging for the suggested 10 hours or if you used more the a 1amp charger the first time.