I can get 30Mbit/s (3.75MB/s) to my handset and they're worried about _10-20MB per hour?_ The problem here isn't the data usage by Niantic: it's the carrier rate plans.
Obviously it varies wildly based on distance to nearest tower and how saturated the band is with other users. "Burst/sustained" doesn't even capture the main variables that would reduce his speed.
This right here is the crux of the issue. Rate plans are straight robbery.