The D-marc has been wind tunnel tested by the BRE (test report 240857) on single ply, bituminous and concrete roof surfaces resisting wind speeds in excess of 105 mph.1: BS6399-2: Code of practice for wind loads.
The BRE confirms that buildings are generally designed for wind speeds with an annual probability of exceedance of 0.02 i.e. a 1:50 year wind speed. If your rooftop demarcation barrier system is intended to be left on the roof for one year or more, it should meet the same design parameters.2: Met office figures
Given that traditional demarcation systems become unstable at wind speeds of 50 mph, it is worth taking a look at the likely incidence of such an occurrence in the UK. If you take a typical UK urban location e.g. Coleshill in the Midlands, figures from the Met office show that over the past 10 years there have been 77 such events.