[D. A. (Tony) Vader]

I have several DW-5600's.

All of them are LE's:

CASIO seems to prefer the DW-5600 for their LE's.

I expect a 40th anniversary DW-5600 this year.

 

[D. A. (Tony) Vader]

I created thread of watches on NASA pictures and despite "common knowledge" about DW5600 it not the most common Casio out there by any stretch. Not sure NASA really tested it the way they did Omegas.
In 90s Timex was official watch with Datalink later substituted with Omega. Casio watches seem to be personal choices. So i think Timex was actually tested because it was standard issue.

According to this, they did:

Does NASA use Casio G-Shock watches?

Answer: The first watch that NASA approved for space was as many knows the Omega Speedmaster Professional. It was the official watch that NASA equipped their astronauts with for the moon missions, and have also equipped the astronauts with until this day. Today they are using the Omega Speedmaste...

www.quora.com

* Not coming from NASA but it looks legit