Picked up a PAYG SIM with 2GB of usage, and I reckon I've used half of it already just speed testing!!
In the office I get 1 bar on my HUAWEI unit and around 9/10megabit download and 11megabit upload. At home I get full signal and using the laptop I managed to see 47megabit download and 20 megabit upload - once.
Problem at home is most WiFi channels are in use, and the MiFi only does 2.4GHz, so its hard to tell if its a 4G or WiFi congestion issue.
One test a minute ago:
My iPhone 5 connected to the same MiFi gets a lot less, I assume it can't cope with the WiFi congestion, and its just slowing down. The laptop (2012 MacBook Air) can. Shame nobody makes a MiFi with 5GHz support :-/
14 years of broadband (ntl: cable to BT FTTC) - Router: Asus RT-N66U - Modem: Huawei HG612 speedtest