I let Desmond play tug of war with his ropes, but he destroys them and I haven't bought him a new one yet, lol. That's the only thing he can tug with though... he tries to tug with his Hollee Roller because he can get such a good grip with it, but I don't let him. That's a fetch toy, it's for fetching, not tugging (it was also $10 and I don't want him to break it lol). But then again, he also has a totally solid "drop it" so I may go out and get more tug toys for him. He lovvessss to tug.
I worry about him starting to tug with stuff other than tug toys, so I've completely discouraged that. If I initiate tug, it's good, but I get really paranoid about him having something in his mouth and not giving it to me/trying to rip it. His "drop it" is so good now that I can trust him to drop anything, even a stick of butter he snagged off the counter.
I suppose I don't need to worry about it much anymore, but I'll still restrict tugging to only tug toys, he's smart enough to understand what toy does what.