Now, there aren't really any reasons to get a Pro over the Air. The only thing holding the Air back with the last generation was the inability to have 8GB of memory in it (hence why I have a Pro). The Air is the quicker machine in day to day use because it has a decent SSD in it now. Really, the only thing that the Pro has going for it is the slight increase in processing power (around 15%) and the keyboard if you prefer it (ie. that doesn't really count, it's a matter of preference).
The memory upgrade, I'd definitely recommend it for your uses.