No, that's not true. It's not as much vertical space as the 13", but it's really not bad typing with the 11" MBA. Same with web pages.
I had a 2010 15" i5 MBP with 1650x1080 screen, sold it, and now my 11" MBA is my primary laptop. I had my 15" MBP for around 14 months, and yet it didn't require a massive transitioning period for me to start working in MS Office.
But despite that, the OP would need to get the 13" MBA if he wants to reliably get 6 hours of battery life.
I had a 2010 15" i5 MBP with 1650x1080 screen, sold it, and now my 11" MBA is my primary laptop. I had my 15" MBP for around 14 months, and yet it didn't require a massive transitioning period for me to start working in MS Office.
But despite that, the OP would need to get the 13" MBA if he wants to reliably get 6 hours of battery life.