In reply to garethb:
Yes. I have had numerous versions of zipkas, tikkas, tikka xps, a myo, 2 different models of the taktikkas (old style with flip red filter, and new style with red leds) for work and they all have suffered from the plastic cracking from the same places as you describe.
I've noticed that the plastic shell seems to have been constructed progressively thinner over the years.
The only one I have had with zero problems was the original e-lite that came in a red pill shaped tough case, still going strong.
In contrast I have also got a black diamond icon (the previous version in lime green) and that is seemingly bombproof. Just by handling the materials you can tell they're all high quality, it's been dropped a couple of times and even in some seriously cold environments I've had no problems with it whatsoever.