Maintaining Up to Date Recovery Partition

Hold on. What you stated doesn't make any sense. If the Mac was imaged with 10.9.1 and could successfully boot from both that OS and that version of the Recovery HD, updating the core OS past it should not stop it from continuing to boot from the older 10.9.1 version of Recovery HD. If you think about it, it would be a huge issue for Apple if this was the case. Regular Mac users wouldn't be able to update their OS without the fear of not being able to boot into Recovery HD anymore.
The only case where this could happen that I know of is if you applied an image that contained an older version of Recovery HD to a Mac that required a higher version of the OS. In other words, if you created an imaging workflow that installed 10.9.3 OS but with a 10.9.0 or 10.9.1 Recovery partition. If the Mac required the higher OS version to work, it would boot up fine, but would not be able to boot into Recovery HD.
Does that sound like what's happened? Because simply upgrading the OS should never do what you just described.

Hmm... It might have something to do with the fact the base image was updated to 10.9.2 via software update rather than a full new image and the Recovery Partition wasn't updated from that either. I'll look into this. Thanks!

But… this still doesn't make sense to me. Just installing an OS update from Software Update shoo;don't cause that to happen. Regular home users would be updating in that exact same way and would have problems later if they needed to do their own repairs on their Mac later, since they probably wouldn't have an IT department to help them out.

As an example, I'm still using a Mac here running 10.8.5, but the Recovery HD partition is still at 10.8.1, from the original OS it was imaged with, and yes, I can boot just fine into my Recovery HD and run repairs. The OS upgrades (Deltas or Combos) don't usually update Recovery HD, because its not necessary in almost all cases. If the Mac shipped with a version it could boot from, as long as it doesn't get downgraded (in the case of hardware that requires that OS version) then it should not need a newer Recovery HD version later down the line, until the whole OS is upgraded, like from 10.8.x to 10.9.x, or 10.9.x, to 10.10, for example.

If that's what happened, I'd be very curious to know the exact circumstances, since this would point to a big flaw in Apple's process. Post back with what you find, because this one is curious.

@pbetancourth - Hi. There is no benefit of updating the recovery partition. The Mac will boot, even if the OS has been updated. Software Update will not cause the Recovery Partition to stop working.

Did you confirm that the Mac was able to boot from the Recovery Partition prior to updating the OS?

I could see this being the case if the included version of OS X was hardware-specific, but base image it was imaged with, was an unsupported system, but was subsequently updated through a combined update to "make it work."

The regular partition would now boot, but the Recovery partition doesn't have the required Kernel Extensions to support to the hardware.

Booting into the recovery in verbose should yield some answers. My guess is that it would kernel panic.

When we initially setup our infrastructure with Casper, imaging was being done with a 10.9.1 version of OSX along with the recovery partition from that installation of the OS. I used Casper's documentation in order to create these Base Images. Everything was honky dory. All worked well. No issues to report. Recovery HD worked.

Fast forward: 10.9.2 is approved to be the default at imaging. The Base Image was updated by downloading the update from the App Store and updating. The Recovery HD was never touched. Currently the image that is being used is 10.9.2 and the subsequent software updates are installed post imaging.

I only noticed yesterday that the machines being imaged were unable to boot into the Recovery HD which prompted me to investigate.