Ours usually take about 8-10 minutes per set, so I'm surprised by how quick yours transfer. (P4P and the latest iPad mini.) Besides the occasional failed upload, this is the only other inconvenience, although a minor one.
I've got a few to do when the weather breaks here and I'll time them to see. It's entirely possible I'm mis-estimating the time required to offload them from aircraft to Tx.
Their app looks like it does a nice job, but as a photographer, I don't like the fact that they claim the rights to the final image, so I won't use them.
You still have your images to do with as you chose. I don't know of any online service similar to Hangar that doesn't also claim those same rights. What we're using them for it fits our model splendidly not to mention the ease of use and finished product in under an hour.
We have some fairly large "Industrial" clients who now request the 360 on every project.