1280x720 video record, no
my personal experience is that 3g eat the battery very fast.
I did a simple experiment. did not change my usage, just turned out the 3g (2g is used), phone wake time dropped significantly.
As i believe i am a bad user for the phones memory/battery it is safe to believe that using just 2g, 2 days are achievable .
p.s. btw, our phone is good in term of hw/radio. we can switch between 2g and 3g without service interruption (i saw some flagman htc devices to require re-registration in the network for the same activity).
So i just added to the status bar the 2g/3g toggle, keep my phone at 2g all the time (except i need 3g) and i am happy with battery now (when screen is off, the phone sleep, before when 3g was on all the time, i observed very large time of phone wake, during screen off)