Nothing wrong with articles on AR triggers, it's the same principle.
The main difference is a sharper and more repeatable break point.
All the 2nd stage does is apply a high mechanical advantage to a portion of the trigger pull to make the first part of the motion easy, leaving a short sharp 'break' on the 2nd stage.
If you imagine you have to move a bar from 0 - 100 to fire the rifle
On our imaginary bar we have a line at 0, and a hard stop at 110
we know the thing goes bang when we get to 100. anything past that is over travel.
If you were to close your eyes and move that line along the bar, you have to pretty much guess, or feel for the 100 and more than likely will hit 100 hear a bang and then very soon after hit 110.
Now we modify our bar with the magic of 2 stage
we allow the first 95 points to move freely, leaving only 5 points that are a little harder to overcome and out hard stop remains at 110.
Close your eyes and repeat, this time you can feel that step at 95, you can feel the change in pressure required, you know your're at the point of firing.
you increase pressure to overcome the step, and after a very short and predictable travel you get your bang, and still a bit of movement as you most likely still hit the 110 stop.
very good, but we can do better.
So you take the screwdriver and fiddle with the adjustments on our bars points.
This time we set the first stage to 98, and we tighten the stop so it sits at 102.
Shorter 2nd stage & less over travel.
We then have a very tiny 4 point gap in which our bang will occur, close your eyes and repeat.
this time the step is so close you know a little more pressure and bang, and when you get the bang you hit that stop almost immediately.
You could go further, you could adjust to 99.5, and 100.5 and you have a hair trigger. where there's such a small gap that the rifle can easily fire by accident.
Spring rifles tend to have slightly heavier triggers than their PCP or Firearm counterparts because the trigger has to hold back the firing force. In a firearm a trigger holds the hammer, in a PCP the valve hammer. in a springer the might of the compressed mainspring in held against that trigger.
I'm sure opinions differ, but in my mind the marks of a great trigger are:
Adjustable (both on the length and weight of the 1st and 2nd stages, and preferably on length of pull and for target purposes angle too i guess)
Crisp - a nice sharp clean break (back to our bar if i set to 95, go at 95, don't start slipping towards it at 93 and actually giving in completely at 96)
Repeatable - there's no use having a great break point if sloppy mechanics mean it moves about each pull. (could also read as reliable but i feel reliability is a combination of traits)
Servicable - remove, clean, grease / oil as required
Different disciplines have different needs, so everyone will rate features differently depending on what is most important to them.
A well designed trigger in a springer makes a huge difference as it will use excellent mechanics to manage that release of force in a safe way while meeting as many of the key features as possible and because the force is so much higher it is a much more challenging design.
HW Rekord triggers are highly rated because of their wide adjustment, crisp clean repeatable break. you can improve them further by giving their contact faces a polish, and to do so is easy because they're in a cartridge that can be removed without serious effort.