There are a gazillion threads on this... But I'm in the don't-secondary-unless-you-absolutely-need-to camp. I.e., if you're racking on to fruit or something like that. I don't even secondary for dry hopping. Secondary-ing will not magically make your final beer more clear - gravity takes care of that, and it has exactly the same strength in secondary as it does in primary. The turbulence of racking to secondary may cause some particulates to clump and fall out of your beer a little earlier than they would if you left it in primary, but they will all fall out after a week or two cold conditioning anyway. No need to risk the oxygen!