I'm trying to choose a configuration of the Base Retina Model...
It would be easier to make a credible suggestion if you told us more about your intended use cases. Based on the way most people use their computers, the actual performance impact of the 13% increase in processor clock speed is going to a be great deal less than 13%. Most applications don't tax the processor to anything approaching the clock speed limit.
The impact of memory is different. As you start to allocate more and more memory, things zip along linearly until you hit the memory limit. At that point the OS begins to swap virtual memory with the disk, and, since the fastest SSD disks are still a great deal slower than RAM, things slow down in a hurry.
The impact of this is that, if you're doing memory intensive things, doubling the memory can have a very noticeable impact on performance. If you're planning on running VMs within MacOS, for example, two things are critical for performance: the number (not speed) of processor cores and the amount of memory that can be allocated to each VM.
Doing what I do, my vote is always for more memory as opposed to faster processors. You should give some thought to what your intended use cases are and see if your decision is the same.
I'm concerned with future proofing the Mac down the line. I'm i need the configurations to be up to date far as long I can.
That's an interesting notion. It also has a great deal to do with your use cases. In my case, I depend on my laptop to make a living. I buy a new one every 12 months or so. My annualized computer costs are typically $500-700 as I'm usually able to easily turn my old one on
eBay in very good shape in the original box. That's cost effective for me. It may not be for you. If your computer is less critical to you, it would make sense to look at a longer life cycle. Still, technology is advancing rapidly. I wouldn't plan on getting seven years of use out of any computer you buy today unless you're just doing web and email with it.
No matter what, you'll get a great computer that will serve you for as long as you need it and will return a decent amount on the resale market when you get ready to move to the next one.
