Apple wants $600 to upgrade from 8GB to 32GB for some off-brand. The RAM was the cheapest part and the easiest RAM swap I've ever done. This particular iMac has a spring-lever on the back, don't even need tools. So glad they didn't solder it. I hear you on the PCI, it's just that we'll never populate 64GB either. It is plenty fast, but I'm guessing RAM is between 4000-5000MB/s and much faster IOPS. It's certainly not negligible on paper. But real-world, maybe it is.
On the DAW, if by flexibility you mean user-friendliness, every DAW is better than ProTools in that aspect. If you mean flexibility in terms of what you can do in ProTools, there's no other DAW that even comes close. That doesn't mean that artists aren't using other DAW's, they are. But recording studios are not. Artists often times start a project in Logic, FL, Ableton. But after that each particular track is exported and loaded into ProTools and ran through a lot of expensive analog gear. Fun fact, Billie Jean was mixed 92 different times. Quincy Jones went back with the mixing engineer and said let's start from square one. The version the made it onto the record was the 2nd mix!
On Apple advertisement, you couldn't be more spot on. Apple has done an amazing job making their customers think they are smart. You will never meet someone who buys Apple products and doesn't think they are smart for doing so. In reality, you can Hackintosh the Mac Pro for literally half the price. Apple builds great products and they make you pay a lot for them. You can even buy a $15,000 iWatch - if you're stupid enough.
On platform, it does present day. I am concerned about future-proofing. Like you said, Apple doesn't update the Mac Pro for years. I think it was 7 years before they released the current model. My biggest concern is about going with a quad-core processor. Xeon is the best, but it's actually benchmarking about 25% slower than this particular i7 because it's 3rd gen vs. 6th gen. The 8-core Mac Pro is about $2,000 more than this setup. This decision is not about the money, it's about long-term stability versus purchasing something that is just excessive. Yeah, the 64GB RAM is excessive, but it was just so cheap I couldn't pass that up!
That's a bunch of expensive RAM. I'm jealous, but not of the price. Wow.
I would not do that. PCI flash memory should be plenty fast for OS loading and operations. It's a total waste to use that expensive RAM for an OS disk, IMHO.
Neat! I've read a number of opinions that Reaper is a "better" DAW than ProTools in terms of flexibility and of course the price difference is pretty huge. I don't know because I'm not in that industry and haven't seen ProTools in something like 15+ years. I'm curious if you have an opinion one way or the other.
This is just my opinion, so take it for what it's worth: It seems to me that Apple builds the Mac Pro platform, advertises it to the world as having crazy incredible performance.... and then sits on it for several years with no updates. Frankly, I don't understand it. I'm not "in the loop" though with Apple, or people who really use Apple machines for "heavy" production, so my view is really from the outside looking in. But it's weird to me.
In general terms though, the real answer for your application is another question: Does your chosen platform (Retina iMac) perform for the tasks you use it for? Are there things that make you wait? If your machine performs well then the answer is probably the less expensive (and rather sexy) iMac that you have now.
Brian.