I still run my TD 166 MkII, all stock, which I purchased new in 1984. I've been through several pickups, older Grado, entry-level Sure, cheap Stantons. A few years ago I upgraded to an Ortofon Super OM-10. While OK sounding, I always found it a bit bright. The beauty of the OM series is the upgrade path - just change styli.
I recently posted a review of my upgrade to the OM-30 stylus in the review section: http://forum.audiogon.com/cgi-bin/frr.pl?ranlg&1236618396&read&3&4&
A few weeks later and I continue to thoroughly enjoy the OM-30. I am transferring my vinyl to CD-R (for use in the car) and I am very pleased with the results! The OM series is discontinued, but you can still find NOS and sellers here on A'gon. I would expect the replacement Ortofon MM line to be at least as good as the OM series, but I can't speak from experience.
Funny you should mention sibilance, though. If the OM-30 has a weekness, it is sibilance. While not a glaring problem, it is just a little bit hotter on sibilants than I would like. It's not horrific, just a little bit of emphasis that shouldn't be there.