Being of a cynical disposition, I think you would have difficulty distinguishing between an Angus crossed with a short legged Dexter and a "lowline" animal. And if you just fancied some small cattle then this would be a much cheaper way of getting them.
So in a similar vein - I've had some very attractive looking "lowline" highland cattle, and we had a perfectly formed "lowline" hereford heifer. (In case you hadn't noticed, I also keep pure bred highlands, herefords , and dexters, and sometimes they mingle amongst themselves. ....)