Boo,
That SSSS sound is called "beter high-end response". It's a good thing, you can also turn down the high-end e.q. boost.
But there's certainly nothing at all wrong with SM58. I've used one off and on forever, and most of the time for the past year. With it, I have to cut the mids (about 1.2K), boost the lows (80K) and highs (9-12k).
With the Sennheiser 855, my mic e.q. is relatively flat.
ALL these mics are way overpriced. Compare them to the Behringers and Samsons and they are 3-4 times as much. And I'll bet they are built any better, or last any longer.
DonM