Coffee Chocolate Cheesecake (Lightened Version)

I stumbled across this recipe in one of my Southern Living Magazines -- apparently the recipe won the 2005 Southern Living Cook-Off. A registered dietitian revamped the recipe to a "lighter" version and it received the same outstanding ratings from the Test Kitchen Staff as did the original version. Here is the "lightened" version. (I'm wondering if you can substitute Splenda for the sugar as well as using fat free half and half). Let me know if anyone tries to do that.

• Ready In: 1 hr 40 mins
• Serves: 10

Ingredients

• 2  cups  crushed chocolate graham crackers (about 18)
• 1⁄3 cup  reduced-fat butter, melted
•  vegetable oil cooking spray
• 4 (8 ounce) packages reduced-fat cream cheese, softened
• 1  cup sugar
• 1⁄4 cup  coffee liqueur (such as Kahlua)
• 1  teaspoon vanilla extract
• 1  teaspoon instant coffee granules
• 4  large eggs
• 4 (1 ounce)  bittersweet chocolate squares

• Mocha Sauce

• 1  cup  semisweet chocolate morsel
• 1⁄4 cup half-and-half
• 2  teaspoons  reduced-fat butter
• 3  tablespoons  strong brewed coffee

Directions

1. Stir together crushed graham crackers and melted butter; press mixture into bottom and up sides of a 9" springform pan coated with cooking spray.
2. Bake at 350°F for 10 minutes. Cool on a wire rack. Reduce oven temperature to 325°F.
3. Beat cream cheese and sugar at medium speed with an electric mixer until blended. Add liqueur, vanilla, and coffee granules, beating at low speed until well blended. Add eggs, 1 at a time, beating just until yellow disappears after each addition.
4. Remove and reserve 1 cup cream cheese mixture. Pour remaining batter into prepared crust.
5. Microwave chocolate in a medium size, microwave safe bowl 1 minute or until melted, stirring after 30 seconds. Stir reserved 1 cup cream cheese mixture into melted chocolate, blending well (mixture will be thick). Spoon mixture in lines on top of batter in pan; gently swirl with a knife.
6. Bake at 325°F for 1 hour or until almost set. Turn oven off. Let cheesecake stand in oven, with door closed, 30 minutes. Remove cheesecake from oven, and gently run a knife around outer edge of cheesecake to loosen from sides of pan. (Do not remove sides of pan.) Cool 1 hour on a wire rack. Cover and chill at least 4 hours.
7. Remove sides of springform pan. Serve with Mocha Sauce.
8. For Mocha Sauce:
9. Cook first 3 ingredients in a small heavy saucepan over low heat, stirring often, 2 to 3 minutes or until smooth. Remove from heat and stir in coffee. Serve warm.