I agree with your provisos as legitimate concerns.

However, I suspect I can get close to "pristine" (ie, not likely corrupted, nascently or otherwise, re 10.7.2 + updated third-party applications) by selecting my first backup as the restore version. [See also below under EDIT.]
The proof of the pudding will be in the eating (restoring), if such is ever necessary.

EDIT:
I'm not sure who among this thread's contributors has or doesn't have Lion, so just let me point out (grâce à Pogue, p 848) to artie and others who don't have Lion:

'When you install Lion, it automatically creates an invisible hidden "hard drive" (a partition of your main drive that has its own icon) called Recover HD. It's a 650-megabyte "drive" that's generally invisible to you. It's even invisible to Disk Utility, so even if you erase your hard drive, the Recovery HD is still there to help you. ... On it, Apple has provided some emergency tools for fixing drive or software glitches, restoring files, browsing the Web, and even reinstalling Lion.'

Last edited by grelber; 11/10/11 12:20 AM. Reason: Lion Recovery HD