The yeast strain can make an impact on a wine (or beer, mead, etc.). That being said, I think the effect is a bit overstated by people at times. Some of the effects may not show up for some time (you need chemistry to do its thing). There's also nothing to say the effects have to be exclusively positive. Factors such as fermentation temperature can make as big of an impact if not more. The only way to know for sure would be to make a direct comparison between two or more wines fermented/aged under similar conditions (different starting strains but everything as close to the same as possible). A lot of people are simply not going to be willing to do that or at least spend the money on it.I used BM4x4 once. It started very slowly. Almost prepared to pitch EC1118 in Day 2 to save the batch. Fortunately, I held the tempt. Fermentation started in day 3. Haha.
After it started, it went very vigorously and finished pretty dry. So far it is still in carboy in clearing phase.
I cannot tell the difference, to be honest. A sales guy in a home winemaking shop said only a few sommoliers or trained wine tasters can tell the difference. But anyway, I bought some different yeasts to try for fun or for psychological satisfaction to be precise. I never have the patience to do a controlled side by side test, since I never try the same wine kit twice. Haha.