Current comparison of NFSv4 with AFS.

[Jesse W. Asher]

Anyone have any real world experience they are willing to share on how 
AFS compares with current implementations of NFSv4?

I'm doing some research on deploying AFS vs. NFSv4 and trying to 
understand which might be better at this point in time for a distributed 
organization with many locations connected via a WAN.  Specifically, I'm 
in interested in the following areas:

1)  WAN performance
2)  Global namespace (transparency of file/directory location)
3)  Caching
4)  Security
    a)  Encryption
    b)  ACLs

I found some discussions in the archives, but the ones I found were old 
(2003) and I wanted a current perspective.

Thanks in advance!