after chatting with a verizon rep i was told, in print, that 20gb of usage with my unlimited data plan on a jetpack would be at 4g speed.
i was also told by a verizon rep in a verizon store that the jetpack wasn't subject to throttling like my smartphone was.
apparently we're mired in the age of misinformation. it took a dozen sources but i've come to the conclusion that 3g speeds begin at 10gb of usage, and prioritization begins at 22gb, regardless of device. i have yet to hear a valid reason for buying a jetpack if my smartphone's hotspot yields the same results (i don't have multiple devices.)