In the past, I've used the 15" retina MBP (mid 2012) along with 27" imac (2014, pre 4k) and a 2010 Mac pro. I've also used macbook air for a year before the MBP and another macbook pro before that. The mid-2012 retina MBP is getting long in the tooth and is having lots of problems with battery and sluggish performance (it has 2.3 Intel Core i7 and 8GB ram). Considering my profession (tech startup) and how frequently i use my laptop, I think having a good computer is pretty important although i'm trying to cut down unnecessary spending lately. Do you think the new 15.4 MBP that has been just updated is necessary or can I get away with the 13" MB?