The other comment I was going to make is it looks like those valves have their inlets on the bottom so to set up a manifold you just run a series of tees on the service line that already have the valves screwed on and then angle the outlet in the desired position and plumb the line out. That is very cool and a great idea.
I found the
Greenlawn website which is where i got to see a better pic of the valves. Nice the company is still in business. I/we don't use poly here but I may see about purchasing some of those valves...especially since your post conveys the endurance aspect of them!
Looks like they run around $30 ea. which is about 3-4 times what I usually pay for a 1' solenoid valve. Might be cool to have a few though for a novelty.