This is fine advice. 8Gb of RAM is more essential than SSD speed for your usage case. 16 Gb of RAM would be (expensive) overkill. To me either type of SSD seems more optional, or as Nacho Libre said "Just for Fun."
I don't agree. I'm running Yosemite on a 4 GByte system, and, it clearly doesn't have enough memory to do "everything". On Mavericks and prior, 4GB was enough, but, not anymore. I have to recommend 8 GB from here on.
I disagree about the SSD part for different reasons. First, on a do-everything box, SSD means being able to edit a presentation, read email, and run a backup at the same time. I'm never going back to hard drives for the system disk again. For the content-server-only case, I would still go with a 256GB system disk and put large content on an external drive.
Now, if they could make it a fan-free Core M, it would be even better, because then there would be no moving parts at all. (Yes, I realize that the graphics are probably too slow in any existing fanless Core M CPU. But, I do like fanless systems.)