Long time Windows user with multiple laptops and home brewed machine. I am debating on a used i7 sp3 or new sp4 i5 I am on the road often and use both a laptop and iPad when on the road. However, the iPad never lived up to my expectations. Therefore my researching the surface pro. The main use is for writing, editing excel, presentations, one note, posting to my blog, and some light weight photo work. My main computer does my heavy photo and video work but there are time when I want to some edits and post to my blog. My laptop is for my day work and the iPad and future surface for my wedding,portrait, and travel photography business. The sp3 i7 sells for less than 1k and a 8gig i5 sp4 is much more plus the keyboard/cover. For those that switched from the sp3 to the sp4, is there that big of a difference? Is it worth the price difference? I am told the cooling system is worth the difference in price. If I buy the sp3 I plan to upgrade the keyboard and pen. Thanks for the in sight!