Before adjusting my water, my lighter beer had a harsh bite to them. they're much cleaner now. I attribute this to the water adjustments.
Me too! My first kolsch was about two years ago, and it was very harsh and a bit astringent. I had an inkling before that about my water, and knew that my darker beers were great. I heard John Palmer talk about residual alkalinity at the NHC in June 2008, and that's what got my mind able to start to grasp water chemisty. I'm a long way from an expert, but with Palmer's book and -th's spreadsheet, I'm finding a vast inprovement in my lighter colored beers.
You've had my lightest colored IPA, and I believe you've had my oatmeal stout. The stout uses my tap water, and the IPA is about 50% RO water and tap water with salts added to get me into a good area for the calcium, sulfate, and chloride. I think you've liked those beers! I know that my IPAs and APAs are much better, and I'm going to be tackling more lighter beers this spring. I know that my Vienna lager is about 75% RO water, and the water adjustments make a huge difference in that beer as well.
My "fizzy yellow beer" for summer was also fantastic, using spreadsheets and adjusting the water.
When you think about it, beer is only four ingredients. If you're going to buy the best grains, hops, and yeast, you might as well work on the water, too!