Rega P9 - need help selecting the perfect cart.

Hi:
I will soon be in the market for a new cart for a Rega P9. I'm currently using the Exact but would like to try something else.
Seeing as cartidges are a little hard to audition, I'd like to hear from anyone with a P9, and try to put together a short list of carts maximum price $1500. I'd really appreciate it if anyone could answer some of the following questions.

1. What cart are you using? What are it's strengths and weakness. (In your system - I know it might be different in mine)

2. If it's an MC - what loading sounds the best? (I currently have an EAR 834P. loading for MC is 510 ohms - I'm considering replacing the phono stage with something more flexible, unless I find a cart that likes either the 510 Kohms for MM or 510 ohms for MC)

3. Are you using any spacers - shims to raise the tonearm? if so how many, and how did you figure out how many you needed? (measurements or trial and error)

4. What is the required tracking force? (I do not want to have to get a different counterweight, so I don't think I want anything that tracks over 2g) I could be wrong on this, but I'm just thinking I don't want to go right to the limit and have the counterweight right at the end of the tonearm.

5. I cannot find effective mass of the RB 1000 tonearm. Does anyone know what it is, so I can figure out compliance, or should pretty well any cart be compliant with this arm? Are there any carts that I should avoid with regards to compliance issues.

Thanks to all who took the time to read all that. I'm kind of new at this cartridge setup business, so if I am way off track (no pun intended) on anything, please let me know.

Thanks
wfs