Though this may not be the exact answer to your question; it's a good indicator.

I'm on 3G+ full-time. Pangani area. For the "average speeds" you'll have to do some Runge-Kutta computations; the thing fluctuates more than the NASDAQ.
At times the connection pops steroids (especially overnight) while at times it lags big time. Then there's the constant auto disconnects/reconnects.

I'm heavy on torrents; I manage to download >4GB on the 7 days unlimited plan each time I top up.