I don't think the .2 bump is worth the price, but you should go and get the 8GB of RAM IMO.
How does the battery life compare between the 1.8ghz and 2.0 ghz versions?
How does the battery life compare between the 1.8ghz and 2.0 ghz versions?
Battery life is reportedly a tad shorter for the faster processor, but this was for the 2011 models.
http://maccrazy.com/macbook-air-2011-i5-vs-i7-is-the-upgrade-worth-it
Good grief, common sense would tell you this.