i have a couple holes in mine in that same area...that spot gets BEAT up...brush and fence catch it pretty regular...
but mine have a neoprene or something under the rubber...i havent stood in water for a long time, but ive crossed creeks that put the holes under water and didnt have leaks...yet...
i wear rubber boots out like noones business...the lacrosses i have are really comfortable for a rubber boot...but werent cheap...but im sure they got their fair share plus some on them between deer hunting in the day and coon hunting at nite in them...