I'm not sure I see any discrepancy or reason for confusion there. The
"balance and bias - and perhaps some product awareness" have nothing to do with the discussion. It's how a potential user balances their budget and configuration, bias toward storage, networking speed, or etc, and what products they're aware of when they plan the config.
Also
there are six (6) TB ports, not four (4), plus an HDMI port. Heck, for monitors there are even USB3 to HDMI adapters these days - and they're fast enough for most graphics work. I was using one on my Dell XPS-12 laptop running PS-CS6 and LW3D the other day and it seemed the same as regular HDMI or DVI to me. I didn't try any games or anything tho.
I guess I'm not understanding why the (probable) fact that only about 10% of people upgrade or expand their machines very much is in conflict with anything said anywhere here or by Apple. Machines always have a certain expansion potential and the MP6,1 is no different that I can see.
Is TB2 "better"? Don't we have to define
better-that-what in order to ask that question? As the MP6,1 is configured from Apple and as shown at WWDC there are already 2 strong GPUs installed so almost no one needs to ask if it's better than PCIe x16 v3 right? What's left? Storage, networking, something else? Well, that's why I said the bit about balance, bias, and product awareness. Everytime I do a search and crunch a few numbers TB2 comes out ahead or the same as what MP5,1 had - although more expensive in some cases. And, in the cases where it was both more expensive
and a commonly employed expansion (such as large storage) there are cheaper ways of implementing it - like via USB3.
What is it you think you're being lied to about?