Line a 9x5x3-inch loaf pan with a double layer of plastic wrap, leaving a 2-inch overhang on all sides. Set aside.
In a food processor combine 1 pound sliced peaches, 2 tablespoons sugar, lime juice and salt. Cover and process until pureed and smooth. Set puree aside. In a medium heatproof bowl, combine eggs and the remaining 2 tablespoons sugar. Beat with an electric mixer on medium speed until combined. Place bowl over a saucepan filled with gently boiling water (the bowl should not touch the water). Cook, beating constantly on medium speed, until an instant-read thermometer inserted in center of the mixture registers 140°F and maintains that temperature 3½ minutes (10 to 12 minutes total cooking time) or reaches 160°F. Remove from heat. Remove bowl from over the water; continue beating off the heat until cooled to room temperature (about 5 minutes).
In a large bowl, combine whipped topping and almond extract. Fold cooled egg mixture, the peach puree and pistachio nuts into whipped topping mixture, leaving some swirls. Pour into prepared pan; smooth the top. Cover with plastic wrap; freeze 6 to 24 hours or until firm.
When ready to serve, toss sliced peaches with honey. Remove semifreddo from the freezer and let stand 10 to 15 minutes to soften slightly. To serve, remove from the loaf pan by pulling up on the overhanging plastic wrap, then invert onto a cutting board and peel off the plastic wrap. Cut into ¾-inch-thick slices and transfer to serving plates. Top with the remaining sliced peaches and serve immediately. If desired, garnish with fresh mint.
Tip: If using a sugar substitute, choose from Splenda Granular, Truvia Spoonable or packets, or Sweet'N Low bulk or packets. Follow package directions to use product amount equivalent to ¼ cup sugar. Nutrition Per Serving with Substitute: same as below, except 148 calories, 20 g carbohydrate, 13 g total sugar.