After nearly a 20 year hiatus to raise our families, we're putting our band back together. One of the guys has kept the PA all of these years, and we're currently upgrading it a piece at a time. During the past 15 years, the PA has either been in storage in a basement, or a dry but unheated shed. One of the Crown amps is shot, and we've replaced it and a couple of other bits are done as well. My question for you all, how well do microphones hold up. We have SM58's, they're all at least 20 years old, and while they still work, I'm just curious if we should consider replacing them as well. Part of what we're fighting is feedback through our monitors, and while we're able to eq much of that out, I just wonder if newer mic's would translate into an ability to sing a little easier. I'm tempted to just buy a new mic, for A/B comparison sake, but I might not buy an SM58, so that wouldn't be a true comparison.