The difference here, though, is that in previous generations, the i7 had other differences aside from just an increase in clock speed. But with the 13" tMBP, literally the ONLY difference between the 2.9 i5 and 3.3 i7 is the clock speed. That's it. So even though I do suspect the i7 will get slightly worse battery life, I think the difference will be fairly negligible.