The Walker trigger is the design that resulted in the lawsuits.
When properly adjusted, consistent, reliable performance is expected.
Improperly adjusted, or fouled, the mechanism can fail.
I like these triggers, have used them for years. But if someone gets at those adjusting screws without understanding what he is doing, or if the mechanism gets gummed up, an unintended discharge can occur.
I have no experience with X-Mark triggers. Just picked up a couple so that I can experiment with them.
The Triggertech units seem to be outstanding.