I agree to the extent that nobody without acreage should consider a heeler mix. We have 20 acres and are surrounded by much larger parcels. Our dogs key on any vehicle that passes on the dirt road 300 yds away, but we've trained them to stay nearby with training collars.
At one point we had trouble with errant cattle in an adjacent field. The heelers enthusiastically helped us chase them out with a 4 wheeler, nipping at the heels of running heifers. Then we got proper cattle guards installed, so those cattle in the adjacent field are now the ones that are supposed to be there. It was not too hard to retrain the heelers to leave those cattle alone. I was worried at first, but they learned quickly.