That's fine until you take your Pro back to apple and they don't have your configuration available and you have to wait 3 weeks for a replacement (this does happen a lot with non standard apple build to order devices). Even worse with an XServe I inherited: they couldn't replace it in warranty. Ended up with a supermicro 1U with debian on it in under 24 hours from buy to install.

My HP: redundant PSU, disks, next day service for all parts or replacement unit.

No competition. I can't afford the downtime.

Visiting an Apple store to have a part replaced is free if your time is worth nothing.

Upgradeable, replaceable parts, redundancy, better storage options, cheaper, doesn't accidentally get trash put in the top. And that's just the case.

I have nothing but contempt for the Mac Pro design - it's style over substance to the extreme.

better as in not needing separate power supplies and cases to have reasonable storage options. better is not needing to buy a new machine (I know, not confirmed but they never aren't offering) to upgrade components. better is having a user upgradeable storage (the ssd is not user upgradable even with tricks according to some).

While it certainly is an interesting case, stylish for some, its pure form over function. They have essentially made a Mac Pro Mini / Mac Pro iPad ... as in what you bought it what your stuck with. Want to upgrade to a new processor or newer video card, well buy a newer machine.

No. The PC is a modular standardised architecture. There are no COTS components that would fit in such a case. This is by design. Apple forked their own design.