I have the Cardas record and have used the concentric grooves on new MC cartridges from time to time, but I still don't understand this idea of having to get to the finish line right away. Maybe I've just been lucky with the brands I've purchased over the years but I have never had the experience of not enjoying a new cartridge right out of the box. How is it possible that the cart sounds so awful in the first 100 hours? I have never experienced that quality, perhaps a bit light in the bass or tipped up on top but never screechy or etched if properly set up. I guess I just take a very different view of the fun of owning and enjoying the process of break in. If there are some records that don't sound perfect in the beginning of a new cartridge's life, I simply choose records that will compensate for the qualities that are slightly amiss. Need more bass? Then put on something with great low end like a Squarepusher or Underworld record and let those highly modulated grooves heat things up and really give the stylus and suspension a workout. Need less tipped up on top? Then put on some Jethro Tull. No, I'm not to going to listen to Martha Argerich play Rach 3 at the get go. But after 50 hours or so, well, heck yeah.
You guys with your needs for instant gratification, settle down!