For the configuration I want, it is 300 cheaper (512 GB SSD), which is a lot. The minor improvements for 2015 I don't care that much about. However, Irs 5100 is slower than 6100. I am not sure if it can handle everyday browsing with a lot of tabs open and with a lot of other (non-GPU intensive) windows open or connect to one or two non-HD displays. My 5-yo old Macbook Pro is struggling to even render the transparency in yosemite. I certainly don't want this to be an issue for the everyday use.