3G does several megabit of download speed. This is the same kind of speed as a lot of users have on wired connections with DSL or even lower-end cable modems in some areas. Also, many users pay for data on their 4G connection, so a game that uses more than a megabit a second to play would be pretty harsh on the wallet. WiFi doesn't have that problem, but then has to share the connection with everything else in the household (Netflix, bittorrent, zombie trojans, WoW patching, etc.)
Good points. I went ahead an tested it on 3G, and to my surprise it worked just as well.
I downloaded a bandwidth measuring app and the game currently clocks in at 0.25 Mbps download per player (upload 0.04 Mbps). I expect that to increase as I add more units including player count and other features (for example chat isn't implemented yet). That said, there are several major network optimizations that I will be making which will hopefully counterbalance a good portion of the new features in terms of bandwidth usage. I'll try to keep download speed under 0.5 Mbps per player which still fits with 3G.
Still thinking it over a bit, but probably going to go with a Nexus 7 3G for Android testing.
edit: Looks like for 3G the Nexus 7 doesn't work on Verizon's network. Right now I'm looking at going with the Galaxy Tab SCH-I800.