Len, I do use a harness. It just happens to be one of the regular styles that you have to spend 10 minutes untangling and then figure out how to put it on. It's rated for 350lbs which gives me the peace of mind.

Most of the vest systems (like most tree stands) are rated to 300lbs. Being a person that weighs in the 290 range I probably exceed the 300lb rating by a few lbswhen I'm fully clothed and carrying my bow and gear. More than likely a device rated at 300lb would do it's job if I fell. But I don't want to take a chance.