It's trivial to figure domains that enter Redemption, as you know just downloading the zone file and doing sort | uniq -u, will give you the domains with changed status (deleted from zone).
The zone file does not include domain name status. It would be be necessary to compare the extracted lists of domain names from two zone files to detect which which domain names from the older list had been deleted. The problem is that the larger registrars, including Epik, no longer leave potentially valuable expired gTLD domain names go through the natural deletion process.
Rather than seeing a domain name drop from the zone, the first sign of a non-renewed domain name may be a change of website IP or a PPC parking/sale page instead of the previous website content. That may not even require a change to the WHOIS record if the registrar is providing DNS service. If the domain name is not hosted on the registrar's nameservers then this information will change and that may be seen in an updated set of nameservers for the domain name in both the zone file and the WHOIS record. (A slightly different kind of changed status to a deletion.) An updated WHOIS record may help determine if it was an expiration shift or the registrant moving to a new registrar. All expiring domain names are not targeted for resale. There are hundreds of millions of domain names that were registered, were deleted and were never reregistered. Some will go through the natural renewal/delete process but may be picked up by dropcatcher registrars if there is some interest in them. Think of it like a trickle-down process.
Previously, this was the cycle: registration - usage - renewal/deletion.
Now there are two paths for expired domain names:
Registration - usage - expiry (if valuable, registrar -> auction site).
Registration - usage - expiry - deletion.
After deletion, the dropcatcher registrars may quickly reregister a dropped domain name.
The "good" domain names are generally moved to auction sites for sale. Beyond the basics, (aged, short, single word, high value keyword, good backlinks, age) evaluating what is a good domain name can be a difficult task. According to some tweets, there appears to be some traffic data on Epik hosted redirects. That can be quite useful in determining potentially valuable domain names.
So I don't think anyone gains any useful insight with the leaked 1 million whois data. Only the owner details of course.
If Epik, or whoever scraped the records, was targeting potentially valuable domain names then it has done some of that research. If there is pricing, backlinks, website authority ranking data and keyword breakdowns, then it may provide a lot of insights.
Regards...jmcc