Thx for the replies. i'm not unhappy with the 2011. obviously old from a software and performance perspective. like an older car, it starts and runs, but some things aren't functioning anymore, needs safety upgrades, etc. i mainly do light work on my computer: word processing/documents, music, photo/video, internet, communications. now that the M4 has become available in the refurb shop, i've considered picking one up (either base or pro). however, in several months the M5 will release. so, i could hold out (as long as mine does), or just get an M4. either way, i expect a significant improvement over my 2011 (though i will miss the built in superdrive, and don't care for the full black keyboard).