DWG's are not, were never meant to be, and never will be, a format to be published over the internet - there's just way too much stuff in a DWG for performance issues. Even with Spatial indexes created it just doesn't cut it.
Having said that, I would definitely move to SDF - use the SDF Loader for batch processing. I only use DWG's for text layers.
Your problem with the DWG not showing up may be the coordinate system used, or lack of one used.
Good Luck,
Scott