Dancing Cartridge.

I've had some similar experiences with a Pro-ject Expression table using an Ortofon 2M Bronze, usually when the musical passage gets really complex on orchestral music. I've had no problems with the same table using a 2M Black or a Goldring 2500. I think the problem lies in the Pro-ject's arm lack of damping, which might make some cartridges with larger stylii (the two you've mentioned both have elliptical) jump around from arm vibrations. My 2M Black and Goldring 2500 have smaller, better-tracking stylii. You might try some tweaking of the arm such as wrapping it with teflon tape to see if it helps. Make sure your stylus force gauge is accurate and set the force to the high end of the cartridge manufacturer's recommendations (although you've probably already done this). If still no luck, you may want to try a cartridge with a finer, better tracking stylus. MM is the cheaper way to go. BTW, the Pro-ject's underdamped arm may also be responsible for its lively and exciting presentation. I've got a room full of tables and arms and cartridges--some costing thousands--and I've had a blast the last few months comparing it (often favorably) to the big boys. IMO the Pro-ject rig deserves a high quality, great-tracking MM cartridge; but be cautious and buy used, in case my whole theory is wrong!

I'm using the Ortofon 2m Black (nude shibata stylus, 22 compliance) on the Expression as stated with no problems. It's interesting that you had no tracking problems with the Pearl, since it's both an elliptical stylus and middling compliance. That might blow up my theory and demonstrate, once again, that audio is all too often just a roll of the dice. But given that the arm is low-mass at 8.7g and the Curl phono section requires an mc, then I'd begin looking for a high compliance(over 20) mc that won't bust the budget. I have no ideas along that line. Another option is to put a decent quality switchable phono stage alongside the Audible. I'd highly recommend the Lehmann Black Cube (used around $200) which I've mentioned before on this forum as getting my vote for the best bargain in all hifi. I still keep one as backup to my Ear 324. It may seem like heresy to do an end-around the Curl, but you'd be surprised at what the little bugger can do, and it would allow you to make choices from high-compliance finer-stylus MMs that are affordable.