I have been impressed with the stock sliders as well. I have seen a couple people whack 'um pretty good and I didn't expect them to stand up but, they did!
I think the only drawback would be body protection. They don't stick out very far.
RedRock just came out with an option on thier sliders if you are looking to save a few bucks. They make some nice, high end ones with a removable skin which is what I will be getting but, they recently released a "skinless" version which are pretty cheap for how beefy they are. I have had a chance to see these in person and they are built very strong. They are frame mounted so they will be very strong and you don't have to drill the body.
Anyway, take a look at these pics...They don't have any up of the "skinless" version yet but they have pictures of the skin version with the skin off. The difference is instead of the box suppports there wil be about 3 tube supports.
http://www.redrockfab.com/shop/jk-rocker-guards/4-door-jk-rocker-guards.html