Hey there everyone, So I have a MBP from all the way back in 2007 and me thinks it's time to trade it in. I'm a grad student now and I'm finding it fairly difficult to keep organized with everything that I currently have. So I'm thinking about buying a 13" rMBP. The problem is that I'm not sure which one to buy. I wouldn't be using the computer as a main one because I have an iMac for that. It'd be more of a computer to use on the go. I usually work off of a external 1TB hard drive but I'm a little cautious about only having a laptop with 128GB space on it. I thought about splurging for the 256 GB rMBP but I'm not sure the extra $200 is worth it. Additionally, I have a feeling that upgrading the SSD will break the warranty on the machine. I'm just wondering what everyone else's thoughts are? Maybe someone can give me a perspective that I haven't thought of yet. Thanks!