Yes I agree. I am also taking a "while I'm in there" approach. I am planning to do the Mporium or Carbahn bolt-on covers. Also plan to replace valve covers, spark plugs tubes, plugs, fuel injectors. (waiting for the EPM billet covers with integrated tubes
info@epm.com 
)
Which brought me to the original question of replacing the entire VANOS unit "while I am in there". It's not cheap for new/rebuilt units, but I can afford it if it reduces the risk of them failing later on. Still leaning towards just doing the covers, since it seems like risk is low of these failing.