7590 batterylife i5 vs i7 FHD model + memory question

Basically what the title describes. Should you expect the same battery-life from 9300H and 9750H model with FHD screen?

Additionally, which memory are used for the different models? 2x4gb and 2x8gb.... Pricejump between 9750H model with 8gb and 16gb is 3 times the cost of a fast 2x8gb (Crucial Ballistix Sport LT) memory kit, and that is WITHOUT subtracting the cost of the 2x4gb kit