Well I had a Lyra Helikon too, and it was a fabulous cartridge. I've also owned Benz Ruby 2H, Koetsu Rosewood Signature, Cardas Heart, Dynavector 20 XL, and many other great cartridges. What stopped my 'upgraditis' was the ZYX line. I plugged a ZYX Airy 3 in, and my Helikon was no longer the 'top dog'. I've since moved up to the ZYX UNIverse, and I am living happily ever after.
I know the UNIverse is expensive, but even the Airy 3 clearly beat the Helikon, and their prices are competative.
Jeff, I would say just enjoy your Koetsu Black for awhile. You made a good choice, now just enjoy the music. You'll find that if you get a 'top shelf' cartridge, it will make you want further upgrades, like a better table, arm, phono stage, etc. So there is a lot more involved than just the price difference of the cartridge. So unless you have $5K or so to put towards analog upgrades, just relax and enjoy what you have.
John