Hello, guys! I'm building an AR for coyote hunting and want to emphasize toughness and reliability. Now I'm looking at Aero Precision MOD 4. Reading feedback and see many good reviews. And what about this Barrel Nut Wrench?

The Mod4 handguard from Aero is a decent choice. Not famously tough, but a secure mounting system with anti-rotation tabs. I am 90% certain, however, that the Mod4 barrel nut uses a standard mil-spec nut wrench, and does NOT use the S1/R1 wrench you linked.