Can’t speak on the hangers cuz I’ve never used them but I’ve never had to adjust pinion angle using 2” shackles.
Fair enough, but that's completely anecdotal, and doesn't mean that your pinion angle was correct/accurate after doing so. If you're only changing one end of the leaf spring, your pinion angle changes. Maybe 2" drop isn't enough to have any significant effect, although I suspect it may wear your U-joint a little faster. Keep in mind that to achieve 2" drop, those shackles will be 4" longer. That's significant IMHO.
I won't claim to be an expert, but spent 20 years in the Jeep world where suspension changes are more common than not.
This is a good general driveline article from Tom Woods:
Driveshaft Angle Explained This video will demonstrate the proper angles for a drive shaft in a stock Jeep or Truck and how the rules change when you add a suspension lift. The video below demonstrates what is happening to the shaft at different angles, how improper angles can cause speed...
4xshaft.com