I know it's been discussed here in other posts - Publisher files can get pretty big pretty quickly, but I just tried two approaches: Import the native Inventor assembly file, and then in a new document, import the exactly same model that was saved as a DWF. Resulting Publisher file size difference: The publisher file created from the DWF is about 40% smaller than the same Inventor Assembly!
Given that there is NO difference in the geometry (because its the same assembly) why such a big difference? I would much prefer the .IAM because it remains linked to the Publisher file and changes in Inventor can just be "updated" in Publisher - but for a 40% memory overhead... Knowing how sluggish Publisher is with the bigger models, maybe it's a trade-off worth suffering?
Re: DWF vs. Inventor. Yes, you have described the current situation accurately.
Although I can't make any promises about specific improvements -- I can certainly say that file size, runtime memory capacity, and performance are all factors that we strive to improve with every release, in conjunction with the development of new features and other improved functionality. It's a balance.
Thanks for your comment ... keep 'em coming.