I'm upgrading from the SP1 to the SP4, expecting delivery next Monday (per Microsoft). The SP4 ordered is the base model. It will be used for "away from home" RVing and playing GenieGO, DVD, BD movies and internet access for communications, finances and browsing. I went with the Core M because of no hard work/use activities and hopefully, longer battery life than the i5 or i7 versions. I keep most of my data on SD cards. I'm interested in any Core M battery life experiences or your use of a Core M configuration to share.