It's what I had been running on my 509 Pro for the last 3 years without a single issue. After upgrading to the latest firmware I have having some issues that it appears the 3.x firmware is causing. Mainly with having an apostrophe in a share name. I can't remove the apostrophe without breaking my xbmc, songbird, lightroom databases. I'm also unable to now setup a new remote replication job to backup that share as it contains an "illegal" character.
I called support today and they didn't mention that.
I'm going to try and first move everything off the NAS to a local drive so that the databases from the share are functional on the local drive. If that works then I should be able to edit the share name and move back. If not, I'll downgrade if I can find the old firmware. Support couldn't find a copy but said they would pass the request on to R&D to see if they have a copy.