I tried substituting many ingredients for this recipe. For instance, made it with whole wheat flour, Splenda, egg substitute, Splenda brown sugar, and fat-free cream cheese.
I thought it took way too long to bake...not 25 min after the crust, but 45 min.!
I thought it tasted terrible. My people thought it wasn't bad, but not quite right. I think they were just being polite. I threw out more than half the product.
If I think about making this again, I won't substitute anything.