Hi HappyMama,
Dates are very high in sugar (mostly fructose and glucose), so don't think you're substituting "healthier" carbohydrates by using them instead of refined "white" sugar (mostly sucrose). If you're using whole, ground dates, at least you're adding in a decent bit of potassium and fiber that you wouldn't be getting from white sugar (which is made from sugar beets), but if you're using date syrup, the potassium remains but the fiber is lost. Calorically, there's really no difference between a gram of fructose and a gram of sucrose. Both deliver approximately 3.9 kCal/gram consumed. If you really want to try cutting down on calorie-rich sweeteners, trying using stevia, or a stevia/sugar blend.(Stevia is not a carbohydrate and is calorie-free.) If your goal is to cut down on fats, however, substitute plain, unsweetened applesauce or mashed bananas for oil, butter, or margarine (these also contain a fair amount of sugar, however).
The recipe you described would give you more of a pudding or a mousse than a cake. You need to add some kind of starch to get the molecular structure achieved with flour. For a higher nutrient value, you can use a whole wheat or amaranth flour, unless your goal is to be gluten free. For gluten-free baking, I use a combination of coconut flour, potato starch, brown rice flour, and tapioca starch. You can also use bean flours, and some people will use sorghum flour or spelt flour (a type of ancient wheat that has a lower gluten content). BTW, true gluten intolerance in the form of celiac disease really only affects no more than 3 - 5 % of the people of middle-Eastern and European descent. Prevalence of gluten intolerance in people of pure Asian or Pacific Islander descent is very low -- almost nonexistant, and in those of Aryan (Indian, as in India) and African descent it's less than 3% percent. It depends on the predominant starch source used during the course of primary evolution. Gluten intolerance is lowest in regions where humans evolved where wheat was not a dietary staple. Most of what you're seeing in the media these days is hype. However, there are other digestive diseases that can often improve if gluten is eliminated (such as Crohn's and ulcerative colitis), and there are also true wheat allergies (which may or may not be caused by gliaden, the protein component in gluten).