Along with the melodramatics regarding the non-retina aspect of the MBA display, the "oh noes! with the 4 gigs of RAM the Air will be a slug!" is the next favorite proclamation.It is such a waste to get the 8GB with your use...especially on an Air.
The airs are already on the way out, if you're expecting to recoup the money in a few years with a sale - that's not going to happen.
You're also not going to notice a difference - so there is absolutely no point in throwing $250 more at it than you have to.
I have found that even when processing video, my 4GB 11" MBA handles the task just fine without breaking a sweat. I've done quite a bit on that little guy and in the 2 years that I've owned it, I've had the fan come on less than a dozen times. I'm extremely impressed with it.
When I first bought it, I had to decide: $450 out-the-door for a new 4GB model, or $650 for a new 8GB. I'm glad I went with 4.