Whisk pumpkin, honey, and spices in large bowl to blend. Set aside.
Stir 1 cup sugar, 1/4 cup water, and corn syrup in heavy medium saucepan over low heat until sugar dissolves.
Increase heat and boil syrup without stirring until candy thermometer registers 248°F, about 10 minutes.
Meanwhile, using electric mixer, beat egg whites in medium bowl to soft peaks.
Gradually beat in hot sugar syrup; beat until mixture is cool, about 7 minutes.
Fold 1/3 of egg white mixture into pumpkin-spice mixture to lighten.
Fold in remaining egg white mixture.
Fold in pecans and toffee bits.
Spoon mixture into prepared crust.
Cover with plastic wrap and freeze until frozen, about 8 hours.