My first experience with slugs was a combat shotgun course given by TFTT. I was using a Winchester Defender with a bead sight and was amazed that I could hit a human-shaped target with any accuracy 25+ yards away. After that, I upgraded to a Benelli M-1 with ghost ring sights and have no trouble putting big holes in the "A" zone on a regular basis. I have the mag loaded with 00 buck, with 3 buck and 3 slugs in the Side Saddle. (It is my primary home defense weapon.) Among the many reasons I purchased the Benelli was the ability to "select slug" quickly and easily.
Once I started designing scenarios for combat matches, I began to incorporate slugs into just about each one that involved shotguns. What really surprised me was the number of shooters who had never shot slugs in the matches, as well as the number who had never even shot a slug round! The payoff was in seeing them realize the accuracy they could achieve with their own shotguns, even with that little bead sight. Now, everyone knows to have at least 10 slugs for each match and they all look forward to using them.
My point? We who inhabit TFL are tuned into a lot more firearms-related issues than the "average" shooter. We need to let those other shooters know about items just like this whole thread. I think almost everyone who has responded to the OP agrees that slugs are an awesome tool that had very real advantages when used properly. Now we need to get our fellow good guys to know that and train with these tools to make them better shooters too.
Don't pick a fight with an old man. If he's too old to fight, he'll just kill you.
"If men are so wicked with religion, what would they be if without it?"- Benjamin Franklin
And, for something completely different: www.kfok.org