Alani will lick the peanut butter out, which lasts about 10 min. and she'll try to get the treats out for about 20 min. before she gives up. The nylabones have teeth marks in them so she must chew on it while I'm at work but I've never seen her do it.
The rope ball was great and it's still surviving although for people who don't like severe messes, I wouldn't recomend it. She got the ball into a fringy rope after about 2 days and 1 week later she still works on each individual string tied in there. So it's been great for her attention span, bad for the house.