Thinking more about this. If the director receives both an -u <feature> and -i<feature> on the same <feature>, it will come up with a plan for an update if a newer version is available. So perhaps its as simple as doing that on all features (except the product itself).
Ideally, I think you should abandon the buckminster install and instead just use the director. An initial install of a fully configured buckminster can be made with one single director call using repeated -i <feature> [ -i <feature> ... ], i.e.,
The trick for update is to just append '.feature.group' at the end of each feature. A call like this:
-u ... -i ...
will result in an update if updates are available.