For various reasons we've gone for a setup where cache busting is provided at a higher level (root of the path) so digesting of any sort isn't useful (actually just gets in the way). Using this gem solves the problem but leaves our asset bundle double the size it really needs to be.
I'm going to patch a fork to include a non_digest_asset_mode or similar setting. Default being copy but optionally move.
Would this be something you'd be interested in?