I have both a lab and blue heeler. Used to have a blue heeler/lab mix.
They are smart as schit adn can be pretty stubborn. My mix was a better swimmer than my lab, faster, adn not scared of anything.
Never took her hunting, but I imagine she wouldve have done ok. I dont know about marking and all that.
Regardless, they are great family dogs if it doesnt work out.
Just remember, they are much more independent and have a mind of their own, so dont expect to have a easy retriever training story. Then again, it may have more "lab" in it and train just fine.
PS, dont let my wife see this, she will want to adopt it.