I always have a feeling that RAM is a conspiracy pyramid scheme.
I keep maxing out every machine I ever get but the difference in performance is never that noticeable.
I'm sure if you put it on the bench it would show improvement but it's never palpable.
More memory won't get your computer to run faster since the apps will use the memory they need, they have no use for extra memory. The problem is when you have a bottleneck and the computer needs more memory than you have available. It will freeze every thing you do. More memory is specially important for multitasking, hopefully you will have a multi-thread processor to match.
4GB is just not enough today. As soon as I turn on my mac, just by opening google chrome I'm already using almost 6GB. 4GB is not enough even for the most basic PC functions nowadays.
I'm happy with 16GB knowing that I'm sorta prepared for the near future (each new version of most apps use more and more memory)