Is there usually a dramatic difference between $5k and $10k cartridges ?

@dwette Your comment is interesting; You have both stereo and mono high end. I am agonizing on upgrading my stereo cart OR add a similar value mono one. I have a lot of mono old rock an some jazz and vocals in mono. Would you upgrade from 5k to 10k stereo, or add a Miyajima Infinity cartridge (and second arm, etc.)? Thanks

Many thanks @dwette I have been asking this question a few times on blogs, and you are the first one to have the perfect setup for proper A/B testing. Maybe I should not thank you as you sent me down the expensive rabbit whole... 

Thank you @dwette that is the answer I was looking for. No speculation on my setup but confirming that the different/better experience with quality mono cart with my type of music. I will buy the Miyajima, or other good mono cart, then try it on my existing system. If that works, then add second quality tonearm. Expensive but fun hobby...It is great to find some that actually have made greater investments and sharing their experience.