One of the most common questions that I get is about the yeast in the kits. Since many kits use the same strain yeast some folks assume that yeast is the lowest common denominator, and that they might do better with another 'less generic' version.
This may or may not be the case: one of the big influencing factors in yeast choice for wine kits has to do with the ability of the specific strain to ferment out reconstituted concentrate—yeast metabolises it differently from unconcentrated grape juice, and some strains may not be able to completely ferment it out. But there's one way to find out if you can make a better kit with a different yeast, and that's by experimenting.
Properly conducted (with a control batch, precise and accurate measurements and good record keeping) experimental trials will yield a rich source of data about which yeast suits your palate, and by continuing to analyse the results as the wine ages in storage, you'll be able to determine if the expected aromatic/flavour improvements fully express, and if they last and evolve and continue to improve the wine after months or years of ageing.
Since every strain of yeast has different internal processes, they each produce different compounds during metabolic activity. Some yeast are more robust and hungry than others and can consume more of the complex sugars in the juice, making the wine drier, others are less tolerant of alcohol and other limiting factors and stop at lower alcohol levels, leaving the wine slightly sweeter. And each strain produces different flavours and aromas in the finished product....