Ha.. the recipe was posted at the request of someone wanting a new low cholesterol lemon cookie, as I recall, so you Low Carb folks disregard it, many on this forum are following other problems than a need for Low Carb info, so pay attention to the posted comments .. :o)
As for Splenda vs Sugar.. it is used at equal strengths 1=1, and has a much higher temperature tolerance than other sugar substitutes. I have used it and found it to be better than others but not exactly the same as sugar.. lets face it, sugar is the only thing that tastes like sugar.
We are striving to find new flavors and tastes that are going to replace the old habits that caused most of the problems that so many people find themselves in today.
We are very fortunate that we discovered at least a reasonable alternative to our bad habits that most of us can live with, and I promise you that you will soon adapt to your new eating. After all, the future quality of your live, depends on it.