I've got a late '13 2.8GHz i7 13" with 16GB RAM. The SSD is starting to get a little crowded but offloading to external drive will compromise what I use the machine for. It runs several (5) Win 10 and Linux VM's (in Parallels) I've got my eye on an refurbed early 2015 2.9GHz i5 with a 1TB SSD and 16GB RAM Question is, how will the 2015 machine compare. I know the i5 has less on board cache but the 2x improvement in SSD read / write time and faster RAM sounds like it might benefit my use case, 1 hour extra battery would be nice too. Biggest concern is the 2.9GHz i5 compared to my i7 CPU right now, doesn't seem like my VM work really pushes the CPU but maybe somebody out there has made this move and can comment ?