Personally, I see them as an opportunity to meet manufacturers or their representatives, who are rather difficult to contact the rest of the time.
It's a great way of networking, meeting people and negotiating things with hardware suppliers, or at least making contact with them.
Who visits them?
![Grin](https://bitcointalk.org/Smileys/default/grin.gif)
Professionals in the sector (manufacturers, miners, developers, traders) and also people who want to listen to well-known personalities in the field on very specific subjects.
I think the best thing for you, OP, would be to go to a few events and you'll be able to make up your own mind about them and their audiences very easily.
Sorry, I don't want to click on that docs.google link, so I replied here.