I have a 1976 337G normally aspiritated and always use full power for takeoff. The engine is designed so that if the throttles are firewalled, there is a richer mixture than when they are pulled back. You can see this by just pulling your throttles back an inch and watch the egt rise. Consequently, you are robbing your engines of much needed cooling fuel at the exact time they need it the most.
There's wonderful article article on Avweb by John Deakin about just this subject. For those of you not familiar, Avweb is a great aviation site that publishes two email letters per week full of all kinds of stuff. It's at
www.avweb.com.
The website for the article is
www.avweb.com/articles/pelperch/pelp0063.html -- if I typed this wrong, just go to the Avweb site and poke around until you find Deakin under "article" or "writers. Very informative especially for turbocharged engines.