I bet plants will love that. All those seeds not getting washed away and all that fine dirt and dust getting caught up in the wonderfull hedgehog and then there's the spores from the moss that grows on roofs......
I notice no prices are mentioned which normally means it's hideously expensive. Then, who puts the hedgehog in place on your two story house or in gutters that aren't accessible? What happens in very heavy rainfall when the brilliant hedgehog slows the run off of the water?
When I looked at local stockists they're all in the wrong place on the map. One place that is in Hove (next to Brighton) the address was Hove but the marker was pointing to the Royal Pavillion in Brighton.