I looked into water out of necessity after an early blush with trying an all RO water with no mods disaster. After that I understood that more than just H2O was needed for a successful fermentation. I later moved to a place where I had single ppm of everything, so water mods were a necessity for every batch. I've found not huge leaps and bounds different brews, but more control for styles and healthier ferments knowing what's going in.
Have any of you noticed major swings in the quality of your beers after water modifications?