So relatively recently (1-2 months ago) I bought a Surface Pro 4, which I love. I would have bought a Surface Book, but they weren't available at the time - I am in New Zealand. Now they're available on a student deal, and I have a friend who'd be interested in buying my SP4. My SP4 is an i5, 4GB RAM. Would the upgrade to a SB be worth it? I'd either get the lowest end model (i5 8GB RAM 128GB) or one up from that, with the dGPU and 256GB. Thoughts? I've heard the battery life on the SB is significantly better, but your opinions would be appreciated .