I started a wine kit a month and a half ago and had decided that since the previous two kits that I have done turned out too sweet by following the directions, that I would try modifying the process. Ordinarily, wine kits are designed to follow the specific steps. I think that for most kits, this would be true.
There are some kits, usually with the term "mist" involved, that are designed to be sweeter and have different flavors than normal wine. Apparently, back in the day of the 80's, there was something called a wine cooler. These used to be made with real wine and were diluted with various fruit juices and water to the equivalent of a 3-6% drink. At some point, the tax rate on wine greatly increased and because beer was taxed so low, businesses used barley to base this type of drink on. Now they are known as malt-based beverage, or malternatives. Some well known ones are Smirnoff Ice and mike's hard (lemonade).
Of course, because they are made with barley malt, this means that they're off limits to those of us with celiac's or have a gluten intolerance. This is where these winekits are useful. They can ideally make a fruity, somewhat sweet drink that isn't too expensive. Some examples of standard types would be like a white zinfandel, or a sangria, but these kits go beyond that by mixing various flavors to make a cranberry red wine, or a tropical fruit blush wine. There's also a new line that mimics traditional bar drinks like the cosmopolitan, pina colada, and margarita. I'm not quite sure what I make of those, and how those could have any benefit over making it from spirits. It only takes a few seconds to make a mixed drink, perhaps longer if you don't have the bottles handy.
Wine cooler kits (mist/breeze wines), do have an advantage to taking a wine and mixing it with fruit and juices. Ordinarily, to make a wine cooler, you need to choose a wine, out of the very many types wine, choose the juices that you wish to mix with them, and then figure out the quantities of each. For example, taking a rioja or temperanillo, or a syrah or other types of earthy red wine, some fruit (limes, lemons, oranges, apples), sugar, some spirits like cognac or orange liquor and mixing it all into a pitcher where it sits overnight. It's hard to have the foresight to have all the ingredients necessary sometimes, plus the expectation to make it the prior day. Wouldn't it be easier to have it on tap?
Unfortunately, in making a sangria, I couldn't compare a version that stuck with the original instructions, and only could compare to two Winexpert kits that I had previously made. Those had been too sweet and I often mixed it with inexpensive wine to cut down the sweetness. When choosing, I had strongly considered doing one of these two to compare, but with my drinkers liking sangria during the summer, I felt it was a good decision.
I decided on RJ Spagnols Seville Orange Sangria and started it per the instructions with the bag of grape concentrate, water, yeast, and I added half of the post-ferment sweetener (the Orange flavoring). I also added a touch of tart cherry concentrate as well. I let this ferment normally, racked it into a carboy with the sulfites to prevent further fermentation and added the remaining sweetener. After letting this clear, I racked it into a keg and the next day had a taste test.
It was agreed that it was drinkable, quite good and not too sweet. The orange stood out and there was a hint of cherry from the cherry addition. I would like to try one of the prior kits done in a similar fashion, to see how it really compares.
These are likely to be the only type of kits that I would consider modifying by adding some of the flavored sweetener to the initial fermentation, and the addition of concentrates. It would be more difficult to try to modify a kit that normally creates a pinot noir, chardonnay or reisling. The primary modifications would be the timing and amount of oak flavoring. Fruit concentrates may be interesting, but it would also risk a kit that takes anywhere from six months to two years after bottling (or kegging) to find out as well as four to ten weeks to ferment, whereas these mist/breeze kits are ready within 4 weeks from the initial fermentation.
Cost is also a factor. The wines that can take several years before drinking (but of a good quality) costs in the range of $US150-170. The lighter kits cost from $US50-70. Granted, the alcohol% is 12% vs 6.5%, but it's easier to experiment with something whose results are pretty quick, rather than take the chance of having something come out okay several years later.
Wine kits:
Winexpert
RJ Spagnols

As your previous posts this post is also informative. These Wine kits is helpful to those who want to make wine at their own home.