I hope the bugfixes also get into 3.8.x.
Phoronix: XFS On Linux 3.9 Takes Care Of Open Issues
The XFS file-system update for the Linux 3.9 kernel isn't particularly exciting, but it does address some open bugs and regressions for this still very relevant and competitive Linux file-system...
http://www.phoronix.com/vr.php?view=MTMwNjY
I hope the bugfixes also get into 3.8.x.
I see that NAS devices use XFS. Does that mean it is better than ext4 in storage role?
I'd recommend a relatively recent talk on the state of XFS:
https://www.youtube.com/watch?v=FegjLbCnoBw
From my point of view, it is the most sane option for a general-purpose filesystem on Linux and will apparently stay that way until Tux3 is ready.
My testing with a heavily used Squid proxy had XFS showing so much CPU load (30.xx and sometimes more) at only 80% file system usage, I had to give up on it. This was around 3.3 kernel. With EXT4, CPU load is usually down around 0.80 as Squid is really not a heavy CPU user, it's a heavy I/O and memory user. Anyway, this was a very negative experience for me and I'll not use XFS again - your milage may vary.