I started off with 2 of the basic ones. Recently ordered one of the pan and zoom models. I put one of the basic ones inside my stand so I could see skimmer cup, water level etc. Another basic one is in the basement where it can see the tank and the dogs when they're in their crates. And the new pan and zoom went on the main floor covering most of the house with it's ability to move.
I told a co-worker about them and I think he's up to 5 of them now. He told a neighbor who now has one, and another co-worker who is up to 3 or 4. I wish I could figure out how to get a commission.
Here's a screenshot of the sump camera right now. Only light on in there is the algae scrubber but you can still make out everything very well (and i could turn on a light in there if I needed through my Apex).