The Sportline splitters are bonded to the bumper in a fashion, but if it's anything like mine then the dealers idea of bonding is a loose term. They are also bolted behind the number plate, and 2 brackets under the arches, along with various clips underneath. They are not too difficult to remove (I did mine a couple of weeks ago, when I glossed blacked all my plastics)
Personally I have grown to love the look of the Sportline splitter, and feel it sets a Black van off nicely, where as i've seen several White vans on here without a splitter at all, and they look the nuts. It's all a personal thing, and I think most of the aftermarket ones look 'w4nk' as the OP so elegantly put it.