Pirate Detection Array 4 was a very useful upgrade for us. As I've mentioned before we have very poor truesec in our rented system. Rents are based on true sec and it would cost us at least triple to get one with high true sec.
As long as we keep it upgraded we get good enough anoms from a cheaply rented system (I'll show you the benefits of level 5 tomorrow as we were able to get that installed yesterday).
Moving from level 3 to 4 gave us a level 10 site (Drone Horde), a level 8 site and 2 level 7s.
The level 8s we have now allow a soloer to chain them for a string of 9 million ticks, with the occasional 19m tick when a Sentient appears at the end of the anom.
The level 10 is complicated. It's a very challenging high value site that we've had fun doing in groups but frankly a bit daunting solo. I'll talk more about that tomorrow when I will be publishing a guest article explaining how to run the site.