TBH Paul, I thought about this but went for it anyway. The fact that it swivels means the dog will be able to maneuver out of a snag better and I really can't see and twig.branch small enough to go through that eye retaining any of our dogs for very long, they would have it snapped/twisted out in a trice and...if they did get snagged.....I would just go to their aid as I would know exactly where they were via the Garmin.
All in all, I decided that there are hundreds of risks to a dog free-running, than the chance of getting snagged on that swivel. Just my own rationale though - each to their own.