I've hit plenty w. Jistic's sliders. The key remember is that with your big hitters, hold up for the first two strikes. If I get two strikes on me, I will protect, but if the count is 2-1 for example, I hold up and if it's a good pitch I'll try to smack it out.
Also, sliders are best if you tweak them. I love Jistic's sliders but I still needed to tweak several sliders to make the game right for me. If you're having trouble hitting homers, bost User Power until you can, and then gradually lower it again.