Yes I remember a few high-profile court cases around “card sharing” – I think the rogue boxes poll a card in a legitimate box frequently enough to keep it active via an internet connection, and multiple rogue boxes can poll the same legitimate box. They are still sold either as packages or as “12 month gift” on ebay – who don’t appear to be to fussed about it. I think this concept has been half cracked-down on, and only works for SD channels. As you point out a very murky and dangerous area.
I think on the linux box I’m going to drop the satellite tuner and put another terrestrial in – making recording and watching simpler. As far as I can tell freesat doesn’t give me much that I’d miss, and it will also make the epg simpler. I’ve tried hanging a portable USB 4.0TB drive off the box and it will use that quite happily in place of the internal 1TB – not found a way to easily access both at the same time yet.
The “bouquets” concept on these boxes is great – you can have the channels grouped (entertainment, news, music etc) automatically, do it yourself, and also add internet streams into your own bouquets which appear as normal channels in the epg. There is also an add-in called “TS Media” that makes accessing Kodi addons much easier.