We are using 3.18.3 and allmost finished with the second broad crawl in 2012.
About 28 TB is harvested and about 18 TB is uploaded this time (about 500-900 GB/day).
We have activated 30 concurrently broadcrawl harvesters during the crawl.
After the manual startup I have no issues with the system.
We plan to upgrade to NAS 3.20 medio august.
We harvest now also facebook.com comments even though we can not see them in viewer-proxy or in wayback