what are some opinions on pivot sliders i've heard good and bad things

I use them religiously. I've eaten it a few times at the track at various speeds from 15-90mph.

Now sliders won't keep your bike damage free but they help alot. Most notably they keep your side covers off the ground so you don't grind through and dump all your oil. This aids in your ability to ride home.

Also you'll still get so scratches and scuffs on your fairings but now the sliders are taking most of the damage and not your bodywork.

Last they allow the slow disappation of energy which helps prevent the bike from cartwheeling once you're no longer attached to it.