So... the OP is suggesting that Ray Allen, arguably the best pure shooter of all time who was one of the key cogs of the 2008 championship who is undoubtedly a first ballot hall of famer, is better than Courtney Lee, a guy who has played a bench role all his life, who's only averaged 11 points a game once. Whatever gave the OP that idea?
We all know Ray had a better career than Courtney Lee will ever have. It's just at this point in 2012, Courtney Lee brings more to this team than Ray would had he returned. Ray is 37, on the downside of his career, and is coming off of ankle surgery for the second time since 2007. Ray's athleticism isn't what it once was, and though he is a lethal sharpshooter, he is only a lethal sharpshooter. That's really all he brings to the table at this point. It's still a question as to whether or not Ray can adjust to a bench role in Miami. He wasn't all that spectacular when he came off the bench for us. Courtney Lee, however, has thrived playing off the bench (where he's going to be when Avery returns to health) for good teams, may not be as much of a pure shooter as Ray but has a reliable 3-ball, brings athleticism and youth, and best of all, he brings amazing perimeter defense.
I'm taking youth, athleticism, and defense over a sharpshooting injury risk at this point.