I own rental too, but the properties themselves are going down in value as well as we speak. Nothing is safe. Property values down, market down, dollar down. Really it comes down to where are you losing the least.
The properties were paid off 10 years ago. The nice thing about industrial property is that a large deposit is required and the renter is responsible for all repairs, ground maintence and business related improvements. Over the years, the renters have made my properties more valuable.