The i7 theories are all based on 'assumptions' rather than evidence.
So ill make some more
From reviews of other i7 devices there should not be a dramatic difference in heat, and likewise whilst working on basic stuff such as browsing the web, checking email etc.. Then the i7 will also give you the same amount of battery life as the i5 as it is not being stressed and they draw the same power.
However when you really need that extra power and you are stressing your hardware, then yes the i7 will likely reduce the overall battery life in comparison to the i5 - however if your running on full tilt CPU wise I'm sure you will also not get anywhere like 5 hours even with the i5 so the difference may not be that dramatic anyway.
More importantly though, The big difference though is that the i7 running full CPU has a 600mhz speed advantage (when turbo boosted) and that will have a big difference in performance over the i5 and I as a user would rather take the extra grunt when I really need it over the small difference in battery life between the two.
