Type Families and defaults

Hi! I see here: http://hackage.haskell.org/trac/ghc/wiki/TypeFunctionsStatus That defaults in type families are not yet implemented. But how far is this? And how far is overall implementation of this? There seems to be a lot of open bugs around that? Are type families meant to be used or is that still an experimental feature? For example, I have problems type checking the attached code (Test.hs). Is there a way to define a default function as I envisioned it? Or is this just broken code? ;-) It seems it is the later as also version with dependencies does not work (Test2.hs). Best regards Mitar