I think it would be a great idea to have known ADS-B status of certain craft.
On the craft live tracking pages (flightaware.com/live/flight/XXXXX) It would be great if there was a way to see if the craft is equipped with ADS-B.
You already have info about the craft in your database (tail number, and etc) you could add an additional column/field that is a simple binary digit stating if you’re ADS-B feeders have reported ADS-B data on this craft in the past. If so, turn the bit on, and display a “ADS-B equipped” button on the page.
You could add the column now, have it default to no, let feeders update it for a period of time in the background, and then tie in the website UI changes later when the data has had sufficient time to collect. Optional: make this information available in the mobile clients.