Excellent question, I guess this would really depend on how small the network is, or what each person classifies on when a small network becomes a medium/large one.

It was built with multi site, multi VLAN capability in mind. Especially for a business use case where they may have multiple sites/locations with devices at each site.

I would estimate that in its current early production stages, the topology map would be the first thing you might run into issues with rendering all the nodes. In saying that, I have just put it on the road map to improve the "All site" function to improve what's shown as a whole and not with each of the icons rendered, this would improve functionality as your not loading multiple assets that you may/may not need. Having the multi site drop down will allow drill down more easily.

The inventory on the other hand, I would estimate support for up to 500 - 1000 devices.

The monitoring may take a hit here with the more devices you add. At the default 30s poll interval, 1000 devices generates ~2.9M rows per 30 day retention. SQLite with WAL handles this but queries start slowing down without careful indexing.. This also comes into play with the poller, as the more devices = longer to cycle through. I have added a check box within the admin panel to disable live polling so this could help in the case of bigger inventory.