Beta 11 was released as a result of a couple of critical bugs found in b9 and b10 and so far it has been awesome.  I saw an increase of about 10MB/s in write performance when moving to b8, but I just now copied about 4GB using b11 and saw another 10MB/s increase!  A very steady 33MB/s writing to a 1TB Seagate 32MB drive in my array.

I’ve also seen indication on the forum that this may also be the end of the annoying video stutter whenever a drive spins up, but I’ve not been able to test this for myself yet (not watched anything as of yet).

Anyway, it’s definitely worth the upgrade if you don’t mind running the beta releases…especially if you want to see a very strong write performance gain.