A few thoughts.
1) I'd be weary of making decisions entirely on breed labeling by the rescue. The breed guesses made by shelters and rescues are notoriously inaccurate. Crossbred dogs are hard to identify reliably, and breed guesses tend to be haphazard at best. Add to that that often they are being made by people without a great deal of breed knowledge. Unless both parents are known without a doubt, don't assign so much weight to breed guesses.
2) I agree strongly with making decisions based on the dog in front of you. Unfortunately, at 10 weeks old, that temperament/personality is going to change. That said- meet the puppy. See how he reacts to meeting strangers. If possible, see him out in the world somewhere and see how he interacts with the world. Starting with a puppy is something of a shot in the dark- whether they come from a rescue, shelter, or known breeding . You don't know beyond a shadow of a doubt what that dog is going to be like when it grows up. You do, however, have the ability to temper that dog from puppyhood. This means control of early socialization/experiences, control of early training, etc.
3) I disagree with describing cattle dogs as having "aggressive tendencies to nip and bite". I think that's an unfair assessment of the breed. They are certainly a "take no cr*p" kind of breed, and can be mouthy as puppies. They can be sensitive to motion, for sure. They also tend to express themselves with their mouths more than other breeds might. Some have trouble with guarding. They're more complex than just "aggressive tendencies". I think deciding against the breed is more about understanding the intricacies of the breed and knowing what issues are likely to crop up in raising one.