depends....i just layed down my aprilia tuono, which comes with integral frame sliders, and they bent the steel bracket they were mounted to. this was a good thing, as the bracket was bolted to the engine mount bolts....better the bracket to give that the engine mount.
on the other hand, frame sliders can mean the difference between cracking a 450 dollar fairing in a tipover, or minimal paint to no damage.
it all depends on the situation you encounter. lowside on the pavement might be alright, but when that bike goes into the dirt and the frame slider digs in (like mine did) things might start bending and breaking