I had a 2011 MBA with 4gb (which was the max you could get back then), upgraded to a 2013 MBA with 8gb. I use software like Final Cut Pro, Logic Pro, FileMaker Pro, VectorWorks, Photoshop, etc. It ran just fine on the 2011 machine. The 2013 MBA is a bit faster, but it's a newer generation CPU and I also have the i7 vs the i5 on my old MBA. The SSD is really fast on the MBA, I'm sure swapping was taking place on the 2011 4gb machine but I was never aware of it. And the new SSDs in current machines are much faster than the 2011 models (especially the 13" MBA).
Since we're discussing the MBA, it isn't possible to have 16gb RAM, 8gb is the max available and it is not upgradeable. Also, there is no law that says you have to upgrade to a new operating system. I still run my 2013 MBA on 10.8 which is the version that it came from. Really not interested in upgrading, I run lots of old software and each new version of MacOSX usually breaks something.
The OP said "I just browse, check emails, facebook, forums, listen to music". Why in the world would he need 16gb RAM?
Since we're discussing the MBA, it isn't possible to have 16gb RAM, 8gb is the max available and it is not upgradeable. Also, there is no law that says you have to upgrade to a new operating system. I still run my 2013 MBA on 10.8 which is the version that it came from. Really not interested in upgrading, I run lots of old software and each new version of MacOSX usually breaks something.
The OP said "I just browse, check emails, facebook, forums, listen to music". Why in the world would he need 16gb RAM?