Was really premium dollar I would say...!
But, let's no discuss prices here...
As for the "american JLC" - due to some import/branding rules JLC was not allowed to brand their watches JLC and instead brand them LeCoultre.
The import rules aslo restricted where the movements were mounted (in US/outside US), how many jewls, and so on...
Do a search in our forum and you will find a lot of it written.
Many of the LeCoultre watches was only sold in North America like this Quartermaster (I have never seen a JLC branded Quartermaster).
The benefit of a 24h dial versus a 12h dial?
Well, you will always know if it is day or night.
Other than that I really don't know if there are that many benifits to gain...
Difference is that the hour hand only rotates once per day instead of twice...
Best
Blomman