Id have to say my BMCs have as much bottom and endurance as any hound ive seen, and i hunt with some good half hounds my friends use, I think curs bay better for sure. Sometimes that little bit of open helps getting the pups out but in general I hate them opening up like "most" do
You're not going to see the difference in bottom and endurance as much hunting hogs as you would certain other types of game like bear. I'm sure there are BMC's out there that can make the really long races but on average and in general I don't think they are even comparable. But most aren't running hogs for six plus hours on one race nor care to so there is no need for that kind of bottom or endurance anyways.
Some breeds and strains just do certain things better than other breeds or strains on average. I have heard of people who have worked cattle with a certain hound or two of theirs but I wouldn't say that hounds on average make as good of cow dogs as certain strains of cur either. There are always exceptions but I am speaking in generalities here.