Hello there, I'm currently in the market for a new computer. I've gotten use to pretty high standards due previous laptops being really good and hassle free. I'm looking at the 15" mbp and considering buying it with a upgraded display. I'm just curious on what i can expect battery life to be under normal usage. Normal usage for me includes a lot of web surfing, writing/reading in word/pdf and streaming music from spotify. I assume this will put me under the 7.5hrs that apple use in their commercials, but how long can I expect it to last? More importantly can i expect it to keep going close to hassle free for 4 years (treated nicely)?