It's just their nature - high prey drive. Most dogs do fine with cats. Sort out the hype and look at the dog as an individual. Consider your situation and expertise dealing with any breed negatives. There are calm Dalmatians, kind pit bulls, etc.
Mixes are usually diluted, more stable versions of the pure breed they look most like.
And, as a bonus, healthier due to hybrid vigor. -Needs Obedience Training . Hot wire along top, fence extensions, invisible fencing. They'll only hit it once or twice. For digging, hog ring welded wire to the bottom of the fence or pour concrete. Many only try to dig out at the gate.