Can you elaborate the last paragraph? In what way doesn't zfs fit? (I couldn't make it out from the first two paragraphs.) Where did btrfs fall short of your expectations? Why would you avoid zfs on general purpose machines if you deem it good enough for file servers?

@arghwhat: To clarify, this isn't a rhetorical question. I'm interested in your technical insight on the subject - especially the comparisons.