I've had my Grado Opus3 wood body cartridge for about 2.5 years now--a bit of a splurge at the time at $275, but money well spent! Since then, I've put over 1000 hours on the stylus. It still sounded as good as the day I released it from its expertly crafted wooden box, but thought it was time for a new stylus just to be safe to not damage my vinyl and to possibly improve the sound.
After searching for options, I went with Andy Kim. I live just a few hours north of his location. That and his reported quick turnaround time made it an easy decision. After some emails with Andy, I went with the top-of-the-line, boron/microridge option. Andy's fast service is no joke--the cartridge arrived at his place in a couple days, and he emailed me that night that it was done. Shipping plus the repair took about a week.
My system is very modest right now, running the Grado on a Fluance RT81 (soon to possibly be a Dual 1229 once it's repaired and there is no hum) into a Schiit Mani 2 preamp, to a Monoprice hybrid tube amp and ending with a pair of Original Advent Loudspeakers.
The upgrade has opened up the top end of the music spectrum. The original Opus3 was no slouch, but I hear a much more airy and open sound, along with incredible mids and bass. The noise floor is much lower, and tracking is phenomenal. Tracks on the inner groove that got a bit rough are smooth and clear. I'm using the Löfgren B arc protractor and have an LP Gear head shell that lets me adjust azimuth. I'm sure I'll need to tweak it a bit as I listen more, but it is sounding amazing right now with just a few hours of listening time. I'm sure some more break in time will continue to open up the sound.
All in all, a very successful upgrade, both for the sonic results and the experience Andy Kim offered. If you have an Opus3 and the means to do so, I fully recommend getting this upgrade. So far, I do not regret it!