Let the hive mind of Engadget get that for you.
"As someone who doesn't reside in the USA, I was wondering what would be the best way to get internet for my computer in the US for a couple of weeks? If it were Europe I know I'd look for some prepaid data. Is there anything similar offered by American carriers? A MiFi or a data SIM that I can tether from would work, but I'm trying to maintain a tight budget. Help!"
Problem with doing a test is that no one will fund it. The industry will, but only if they're sure the results will be what they want, like the big Danish study on cell phones recently that concluded they don't cause brain cancer. Only thing is, they defined a regular cell phone user as someone who uses their phone once a week for six months. Now why do you suppose they did that?