I don't really see the Giant part spec as being much better. Pretty much a wash in my opinion. The Fox is a much better fork, so that kind of evens it out.
You would need to ask about the service history of the fork. If the fork didn't receive regular service(at least once a year), it is possible that the stanchions are worn and could need to be replaced. Also ask about when the seals have been last replaced -- this is a wear and tear item. If you see any oil pooling up around the seal wiper or signs of oil dripping down the lower legs, that is a sure sign of worn out seals.
Here's what my friends Fox 36 stanchions looked like when I recently serviced his fork. This is what happens when a fork hasn't received any maintenance:
Typically, that kind of damage can only be seen when the lowers are removed.