Depending on your scope, the filters likely wont fit. I know they dont for nightforce because the threading is different.
If you do get a filter, make sure it is a high quality one and multicoated, Good quality filters cost 50-100 dollars depending on the size.
The degradation in image quality will be noticeable with lesser quality filters at longer ranges.
Some high end camera lenses like Canon have sacrificial lenses built in that are not part of the optical forumla when expensive ED glass is used. It would be interesting to see the same features in rifle scopes.