Interesting- I'll have to keep an eye on this. Have you installed it yet?
I upgraded my drive to a 1 TB SSD and just installed YaCy - seems ok so far. It's not going to replace your regular search engine right now, but it is very promising.
You can browse it at http://localhost:8090/
I find I'm getting a lot of German results, but, it's still small, so I guess I'll run a node for now & hope for more people to jump on board. It will improve 1 person/installation at a time.
In a quick test, I started crawling my blog site, then searched for the title of an essay that I mirrored on in after giving the crawler some time. My blog post with the mirrored essay came up, but the original essay didn't. No real surprise there. But it shows that crawled searches from your local crawl come up darn fast.
The administration interface is very good as well. Lots in there. I've not explored it all yet, but it seems quite robust from a quick browse.
The quality of results is not at the DuckDuckGo or Google level yet, so that's a problem. I suppose that what YaCy needs is philosophically aligned people to start running nodes.
There are some interesting things that you could do with it though. For example, you could run through TOR, crawl sites that you are interested in, e.g. https://publicintelligence.net/
(a subversive site - they even host "Inspire" magazine!), then later search your own local cache in stealth mode while not connected through TOR. Since you'd have that locally stored, you'd never access the Internet (stealth mode) and could get search results without anyone knowing -- it's all done on your local machine. tl;dr
- Great software. Network isn't prime time ready yet. Needs more privacy advocates to add nodes for network effect to start to take hold.