I am going to buy the Sigma 70-200 af f2.8 apo ex os hsw + sigma 1.4x ex apo dg converter. My question is if I buy it from what they say is an grey importer ( cameras direct) I know Sigma like Canon wont cover these items. But if I purchase a warranty (3yr mack) from them as well will I still be able to get it repaired. I have not used one of these 3rd party warranty companies before so I am unsure how they work. Who does the repair work for mack if it's not Sigma or Canon ?