Microsoft's Windows 8: Will it breathe new life into older PCs?

With Microsoft making available the final released to manufacturing (RTM) Windows 8 bits to some customers starting on August 15, it's a good time to contemplate whether it's worth grabbing them.
Yes, Windows 8 is a touch-centric operating system which will work best -- or, at least, most like the way its designers intended -- on touch-enabled tablets, PCs and monitors.
But I've heard from several readers that they believe Windows 8 includes enough under-the-hood improvements in security, reliability and performance to convince them it's worth putting on older, non-touch enabled hardware, too. Even without (or despite) the new user interface and touch gesture support, the rest of the OS is a worthy upgrade, some claim. They like the less flashy features, like faster boot times and fewer required restarts after updating.
One reader made this case recently:
"Sure, the new Metro UI still ticks me off, and there are obvious ways Microsoft could have improved this for legacy Windows desktop users - but I am learning the overall O/S improvements are worth it. My key favorites are (1) Installation and boot are much faster, and for a software developer like me that is really huge. (2) The new Windows Explorer is much better with more functionality where you need it. I love being able to just double click an ISO file and open it like a ZIP file. It is also an easy way to get to the Control Panel. (3) Fast and fluid really is a noticeable improvement as I have grown too much gray hair waiting for the Windows UI in the past. (4) Storage Pools - it's about bloody well time - and they even work with USB devices. (5) Single cloud-based login - again - it's about bloody well time. For sure there tons of stuff that still need improvement, such as, the Metro Style Mail app is buggy as hell and the UI has serious usability problems, but still prefer Thunderbird so I don't care."
Jeff Atwood, one of the founders of Stack Overflow and author of the "Coding Horror" site has been upbeat about Windows 8 throughout its development. Last week, Atwood tweeted about Windows 8's superiority over Windows 7 "in every way," specifically in install, boot, sleep/resume and file operations.

Even ZDNet's own Adrian Kingsley-Hughes, not always the biggest Windows and Microsoft fan (to put it mildly) has found Windows 8's performance improvements to be measurable and noticable.

The Windows 8 team hasn't really pushed these performance enhancements anywhere as much as they've emphasized the more controversial touch/UI elements of the operating system. Sure, they have explained in great (and lengthy) detail a number of the performance tweaks it has made to Windows 8. But they really haven't said expressly -- or, at least, succinctly -- that Windows 8 could revive an existing/older PC.
This does seem to be one of Microsoft's claims, however.
"Windows 8 improves on Windows 7 fundamentals like speed, reliability, security, and other essentials that are important to IT administrators. And it works seamlessly with an existing Windows management infrastructure," said a Microsoft spokesperson when I asked about specific improvements in Windows 8's existing features that could benefit users with older, non-touch-enabled PC hardware. "Even on lower-power systems, Windows 8 is responsive. Your PC starts quickly, your apps run faster, and you’re more secure from start to finish."
Users who install Windows 8 on older/current hardware will be able to take advantage of the cloud-syncing and roaming settings support in Windows 8, the spokesperson added. With Windows 8 Professional and Enterprise (note: Enterprise requires users to have a Software Assurance contract with Microsoft in order to install and use), BitLocker enables faster hard-drive encryption, the spokesperson said. And the new Windows 8 refresh and reset settings could help those needing to restore even older PCs, the spokesperson noted.
Microsoft, which is now both the software maker and a Windows OEM, no doubt would prefer users to buy brand-spanking-new Windows 8 PCs and tablets, just like other PC makers would. Maybe that's why we shouldn't expect too much marketing/advertising fanfare, if any, around the "Windows 8 makes old PCs run better" concept.
But even without a Seinfeld to convince them, some Windows users with PCs that meet the minimum Windows 8 specs -- 1 GHz or faster processor;  1GB (32-bit) or 2GB (64-bit) of RAM, and a DirectX 9 graphics device with WDDM 1.0 or higher driver -- say they're finding Windows 8 to be a nice performance booster.

Any others with an older Windows PC now running Windows 8 have feedback on this one? If Microsoft hadn't Metroized/modernized Windows 8 and made it more of a Windows 7.5 upgrade, would it still be worth an upgrade?

Update: A couple of good points from the Twitterati. Some point out that netbooks, with lower screen resolutions, aren't really very good candidates for a Windows 8 upgrade. And others noted that users should be sure there are drivers for their older PCs that work with Windows 8, which won't always be the case.