What, if any, benefits did you see from using it?

Never saw a need to use it. What conditions are you having to inquire about how well it works?

Does the same thing as lapping compound.

I have a barrel with 2000 + rounds through it. Thinking of trying it out to smooth out some of rough spots in the leade.

I've used it on 2 rifles, my son's Marlin X7 270 Win and my Savage 12 FV 223 Rem. Now they don't foul as easily and are easier to clean. The accuracy is excellent on the Savage with consistent 5 shot groups under 1/2". Didn't notice any accuracy improvement in the Marlin but didn't hurt it. The only problem with the savage is it take 150+ rounds after I clean it for the groups to tighten back up. The the accuracy lasts for few hundred rounds after that.

Is that a typo?

I'm a believer in keeping metal fouling well under control and I'm okay with with firing three to ten or twelve shots to bring the bore back in, but that's beyond reason.

Have you tried other bullets just to see about their metal fouling properties? Beyond that, I think I'd look at various chemical bore treatments (can't recall the name of any of them though...never used any).

Not a typo, after a thorough cleaning the the groups open up to over 3/4" at 100 yd. Takes a lot of rounds to get it back to the .5" range. Now I don't clean it until the groups start to open up again.

Here's a photo of a 8 shot group I shot at Elm Fork last weekend.