WOW, this is great insight. How many of us can compare several generations of the same bag all at once? I was just thinking about this since I just picked up a Costa Rico station bag.
I have 2 Costa Rico bags a murphy K8P- 9930 and a Station D9P- 5130. Both feel great however, the Murphy which I believe is slightly older feels like better leather. Not sure but the other bag may be a rerelease? My Creed reading sucks, but I think the bags were 88 and 89 or is that 98 and 99???? What the heck does that P stand for????
My USA leather on my older bags feel slightly more lush than the Costa Rico bags. Zippers and hardware feel sturdier. Since the styles are different though, I can not make concrete observations on the two. I see no huge differences.
1998 and 1999. Bags made before 1994 didn't have any manufacturing or style codes in their serial number. Read and study this, there will be a quiz on it tomorrow

http://forum.purseblog.com/coach-shopping/answers-to-authenticity-questions-94198-3.html#post1944848
And the third digit "P" is Coach's code for the Costa Rica plant.