I bought an SP4 M3 about 2 weeks ago and I really like it but, I am really concerned about battery life. Today I was at lunch and did light web surfing and dropped to 80% in around 30 minutes. That works out to be roughly 40% per hour and 2.5 to 3 hours of battery life overall. I had screen set to 50%. I looked in settings to see what used the battery and it mainly showed IE which is what I was using. I went out after lunch and bought a base model Surface Book and I really like it also. If the extra weight will get me extra battery then it will be a keeper and the SP4 will be returned. The larger screen of the SB is great and the tablet portion seems much lighter than the bare SP4 but they are nearly the same. A kickstand would be nice but I have found myself reversing the clipboard on the base when sitting on the couch. I think if I keep the SB I will soon get the larger charger of the i7 model to bring charging to around 2 hrs instead of 4+ hrs. I will miss the small carry around size of the SP4 if I keep the SB, but I need battery! Let the battle begin.