Hardwood floors in upstairs unit?

[Mike P.]

It's time to replace the carpet in my upstairs unit. While removing the carpet, however, i discovered underneath the carpet was a layer of stick on tile, then hardwood floors. My question is how much nosier really are hardwood floors to the downstairs tenant, if I were to sand and refinish them vs putting down carpet? Anyone have hardwood floors on their upstairs unit with no problems?