Im a class A (USCF), but have gained about 200 elo points per year.
I know no grandmasters play the Danish gambit in tournament games, but have any actually said not to play it? If so, who?
I know GM Boris Alterman and GM Hikaru Nakamura both play the gambit in blitz games and simuls.
The Danish Gambit is very popular in Correspondance games and is played by top players like:
N.A. Preo, Kampfhenkel, Firnhaber, J. Barrios Troncoso and Dubini.
I routinely beat my computer (Fritz 8) with the gambit.
Anatoly Karpov drew against the gambit in a rapid tournament
In Nunn's chess openings, the opening is given the evaluation unclear, and Nunn says that "the gambit deserves more respect than it is usually given."
--Non-GM Tartersauce