I, also, have noticed no difference ( apart from the cash left in my wallet
) sugar wise. Also, they give you FAR too much potassium ( or sodium ) metabisulphite [ about 5 times normal ]! It comes out so chemically. Homebrewers usually use 1 campden tablet per gallon to stabilise. That is about 0.44 grams or something, or a 16th of a tsp of powdered meta, easier to measure than you'd think. A £1 measuring spoon set has 1/8th tsp usually so just judge. The kit gives you something like 5 times what you need, and the clearing agents seem to contain a bucket load too. Maybe use bentonite then Vinclear, I find that works a treat and no off flavours.
That's my two penneth :