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

At that level there is generally not a dramatic diffeence between any 2 components  You're chasing the last few percent.  that is not a bad thing.

Now people will get very excited when they make progress.  Lets do the math with some made up numbers to illustrate:  you're at 97%.  You find a component that moves you to 98%.  It is only 1% improvement but it got you 33% of the remaining and it is a big deal to you. 

Jerry

@noromance : $10K to make an excellent phono cartridge? Really? Let’s assume an engine for a BMW automobile costs $10K to build. I can understand that. Plenty of parts that must be machined to tight tolerances and then skillfully assembled by a team of workers. A phono cartridge is a small device that weighs several grams. I fail to see where there is $10K worth of parts and labor.

Are you using a SUT?

If so which one. I think a $5,000 cart with a great SUT would be better than a $10,000 without a SUT. 

@martinl07d : The $16K Grado Epoch is a moving iron cartridge so no SUT needed.

Jason was kinda focused on dwette post. 
absolutely no SUT needed on MI