@tomic601 Peter calls it jitter. I call it miss-tracking. I have heard the Red but not the Blue. They are good cartridges, but I prefer the Soundsmith, The Zephyr MIMC is 2K and a great value. Soundsmith's customer service is second to none. I can recommend it without hesitation. This is not the case for some companies, I am not familiar with Excel, but I have interacted with MSL, Ortofon, Grado, Lyra and Soundsmith. Soundsmith handily wins the customer service medal.
@rauliruegas I have looked at many styluses under a microscope. Unfortunately, my ability to take pictures is recent and I have no photos of older cartridges to demonstrate my point. I'm sure your Excel cartridge is excellent, but that is an anecdote. I have seen all sorts of defective styluses and mountings coming from very reputable companies. The quality of the diamonds and polish is very variable. It is extremely easy to see. In general the more expensive cartridges get better styluses, but "more expensive" varies from one company to another. You can get an excellent stylus in a $600 cartridge and I have seen a defective stylus in $10,000 cartridge.