I am interested in obtaining a G Shock DW5600 and have noticed there are a few different models ones cased in either china, Thailand, Singapore and others? Module #?Also looks like the newest version is 100% plastic and not stainless steel like the ones prior. What are folks impressions on the new ones compared to the previous version? Also which one is the one NASA allows? Lastly, if you were to buy one new which one would you buy and why and if you were going to buy one second hand which one and why? Thank you..