anyone use a Mac's River Runner

I have a buddy looking to put a Mac's River Runner, Prop Protection & Accessories, Boating Outboards & Accessories, Boating : Cabelas.com on his 25hp mariner thats on the back of his supreme boats trout fishing boat he use on the white river. Has anyone use one of them before? How while do they hold up to rock and shallow water?

I have a Mac's River Runner on my 25 hp Nissan on a 207 Supreme trout boat that I fish the White River with. I wouldn't put in the river without it.