Welcome!
The answer is....it depends! Some rules don't allow one piece axles so you'd have to use nails. Classes with wide wheels generally run faster when the rear wheels are canted which is harder to do with a one piece axle. Some guys running bearing razors like the aftermarket (not Pinecar) one piece axle since they mostly run with no cant in the rear. They feel it guarantees better rear wheel alignment.
The one piece Pinecar axles use plastic hub caps also. If one comes off you may lose a wheel. I don't believe they are reusable so if you have to remove a wheel, you will need to purchase spare hub caps.
I understand that some folks that are required to use only the one piece axles have had success with chopping the axle in half to allow for canting....as long as the rules don't specify that the one piece axles have to stay in one piece.