No I haven't used it. It is on my list of things try. However I know someone who said it helped her.
Here are some more links for Lactoferrin. Research ha been done into both human and bovine (cow) lactoferrin. Most commercial lactoferrin is bovine, which is fine bcause it seems to be at least as good as human lactoferrin in fighting pathogens. There are two main types of bovine lactoferrin, of which, the iron-free form (apo-lactoferrin) seems to be best at killing pathogens.
One source said "An adequate and cost effective dose of lactoferrin for the adjunctive treatment of disease is estimated to be 300 mg a day".