retina macbook pro (2012) vs vs macbook air (2014)

Hi Apple community,

I'm struggling with an issue and I need user and/or expert input. I presently have a 2012 retina MacBook Pro, 2.5GH processor, 8 GB RAM. I purchased it in early 2014 to use for school and personal use. My main uses are web surfing, email, lite photo editing, lite movie editing (using iMovie), creating word docs and working with spreadsheets, often multitasking between several of these apps. I love the system, it's fast, and the Retina screen is great. Here's my conundrum - would a 2014 MacBook Air with a 1.5 GH processor and 4GB RAM be as good as or better than the 2012 MacBook Pro? The reason that I'm even considering the 2014 Air is the long battery life, but I don't want to sacrifice performance for just a few hours of battery life. Also, my budget is limited to about $850, which would come from the sale of the retina MacBook Pro, which means I'm looking at the refurb Air units from Apple's refurb store (no extra customization).

Anyone have any thoughts or comments?