So I think the point here is, what is more important the speaker or the networking? I run business events at a members club called Century which is perfect. We have about 80 attendees to see our speakers, then afterwards they are taken to a roof terrace where they can network.
The worst thing to do is compromise the quality of the talk, if that is the reason why people are attending. I have been to many speaking and networking events where people are forced to stand to watch a speaker. Sometimes these events are in bars which just have a reserved area, not even a function room.
So ideally, have two distinct areas, one for speaking, one for networking. It works much better this way!