I haven't used a spring-loaded firing pin, myself.
I bought a replacement pin because I was scared of slamfires, and have had no issues.
In all of my research, it seems the majority of the people who have bought a spring-loaded pin did so as a preventative measure, and not because they had an issue with slamfires.
The majority of those folks love them, every once in a while debris gets trapped in the spring, defeating the purpose, but everyone who has one tends to love them.
I don't know if this helps, but TL:DR is that they work. I just haven't seen the need yet, myself.