DOM4 considerably simplifies Attrs (http://www.w3.org/TR/domcore/#interface-attr). DOM2 has them be full-fledged Nodes. We need data on how safe implementing DOM4's version will be. If someone instruments Node to log to Chromium histograms everytime an API is used on an Attr, then we can get data and make informed decisions. The new API is 1000x better, so the more of it we can implement the better. The parts we're worried about implementing should be brought up on www-dom@.
> The new API is 1000x better For completeness, could you explain some ways in which it is better?
The main difference is that they are not Nodes anymore. They are (hopefully) just the minimal interface required by web compat. This makes Attrs a lot lighter-weight (e.g. don't need to have member variables for child nodes) and gets rid of non-sensical APIs (e.g. appendChild to an Attr). In terms of WebCore implementation, it may eventually allow us to remove the distinction between Attrs and Attributes.
One place where attribute nodes are particularly visible in the platform is XPath.
This is more or less complete now. Any further improvements should have more detailed bugs.