the bullxs that i have seen work, including the one that i own have been good dogs but there down fall has been stamina. my bitch will hunt cover all day like any other cross, but once she starts running flat out, like lamping lots of rabbits, the lactic acid builds up. she will run to a stand still till she cramps up. she reminds me a bit like frank bruno,lol....just a little bit too much hard muscle...great for a while, very fast but can only be pushed so far.