Measurement of mash pH and fiddling with water didn't improve my beer. If anything it made my beer worse for several years until I figured out my pH was much too low and that I should really be aiming for 5.5 to 5.6. Beer's gotten better since then. Everybody will tell you to aim for 5.2 to 5.4. That ain't right. Now I aim for 5.5... which incidentally is about my average pH before I really knew what I was doing anyway.
The most important water treatment you can do is to eliminate chlorine with Campden, and to ensure you don't have a lot of nasty iron, magnesium, sulfate, or alkalinity (unless brewing a porter or stout then alkalinity is good). If you have all those bases covered, and have been pleased with your beers up until now, you can safely continue to ignore the water baloney and just brew on. I wouldn't say any of this takes the beer to the next level, not unless your water is really horrible.
