Opinions are going to vary on this topic.
301 redirects no longer preserve and pass all of the link juice that they once did with Google. If you have invested a lot of time and effort into link building, then you are probably better off staying with the .org domain and 301 redirecting the .com domain. You will lose link juice and PR with a 301 redirect, but it is your best alternative if you need to change the focus to the .com.
A .com does not have any ability to rank higher than a .org domain. .com, .net and .org can all rank equally well. The advantage with a .com is that this is the first version of a domain that people remember.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin