It really does not matter which type of concentrate you choose. That is just part of having a complete fermentation. When you get to the point where you are ready to bottle, that is the time to make your wine sweeter. You add wine stabilizer such as Potassium Sorbate to your wine. This stabilizer will keep the wine from refermenting. Then add sugar back to the wine until you reach the desired sweetness you are looking for. This gives you complete control over how sweet the wine is going to be.