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!