Having been on Orange at work, and then transferred to T-Mobile, I find it hard to believe the EE's service will provide anything like this kind of throughput. You'd be lucky to hit 500MB downloading non-stop for a month.
With Orange, the 3G data service was frequently utterly unusable. Imagine coming out at Oxford Circus in London and trying to use maps on an iPhone and giving up waiting for it to load and it being quicker to walk around Soho in circles to find your intended destination. Or taking the train to Edinburgh and data connections timing until shortly after leaving Newcastle when suddenly the connections starts flying (bandwidth shaping or over-subscribed?)
On T-Mobile, when my connection stalls, I find I have a T-Mobile Orange signal. Forcing it back to T-Mobile fixes the throughput. Recently a colleague was changed to EE and seems to be only getting Orange's data service.