Sanding screen vs Sandpaper for hardwood floor
I have years of using both.  I have no scientific data or anything like that.  If I had big pieces of lint/whatever stuck in polyurethane then I would use a sanding screen.  If I had a large area of issues I would use sandpaper.  A screen will allow you to knock out things that are not flush with your surface while leaving your surface in tact - see @DA01's comment.  

What I am not sure about the comment is for fine sanding.  Yes screens are great when finishing off drywall mud when you have a few bumps but they are really good at any point where the area you actually need to sand is a small percentage of everything.  Screens are for when there are imperfections littered over your surface, sandpaper for the whole surface (think divots and air holes).  

I find that sandpaper is more precise, and i feel that screens last longer and pick up more mistakes.  This is scientifically proven because I use screens a lot and my drywall pros never do.