The advantage of the quad core is dependent on the applications you are running and the specific mix running at any give time and is well beyond my ability to quantify. The extra 8 GB of RAM would come into play when you have lots of applications open and/or applications that require a lot of RAM. To be truthful those extra 8 GB have less performance impact with the vastly improved memory management techniques that were introduced in Yosemite.

Given the certain release of iOS 10 concurrent with the probably release of the iPhone 7 late this month and the fact MacOS 12 and iOS 10 beta releases have all been tightly synchronized you shouldn't have long to wait for that new hardware. 😉

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein