Are Knipex locking pliers worth the premium over Irwin?

It depends on the use case. Specialist subreddits like r/Tools repeatedly praise Knipex's release mechanism and jaw geometry as best-in-class, but they also note that Knipex's locking pliers don't have the same dominant lead they hold in pliers wrenches and Cobras. Several r/Tools threads even flag Knipex's locking pliers as having softer jaws than expected. If you want a Knipex specifically for grip force, the Universal Grip model is well-regarded; otherwise an Irwin or Klein delivers most of the performance at a much lower price.