I'm awaiting a repaired and upgraded cartridge due to arrive any day now from Axel Schürholz at schallplattennadeln.de. The stylus will have an ellipitcal rather than the standard spherical diamond. I will let you now what it sounds like on my Beocenter 1800.
In the meantime I recently received an almost new MMC 20S cartridge complete in it's original packaging along with brush via Ebay. This has been fitted and the sound difference is certainly quite noticably clearer, louder and with much better low end frequencies than the the rather tired MMC 3000S which it has replaced!
I will post again when I've fitted and tried the MMC 20S from Axel and let you know the differences.