Fruitsalad....it is difficult to compare dose and effect with pain killers as people respond differently unlike antibiotics where one can more easily compare doses.
Naproxin 250 mgms in my opinion is a modest dose....very modest and one should take the dose that relieves the pain, depending of course on what the pain is due to.
If Ibuprofen 400mgs is not relieving your pain...then try Ibuprofen 600mgms.