AT OC9 MK3 compliance to high for a Rega RB 1000?

Hi everyone!
Purchased a Rega P9/RB1000 about a month ago and have been researching many low output mc cartridges. My phono preamp is an Allnic H-1200 and the AT-OC9 has been a very successful match in other systems. As most of us know Rega does not give the effective tonearm mass for the RB1000. Audio Technica states a dynamic compliance of 18cu at 100Hz. To get the standard 10Hz number you need the dynamic compliance of 18cu x (1.5?) = 27cu. If you estimate the effective mass of the RB1000 at 12g?+ 8g OC9 +.5g mounting screws = 20.5g/27cu = 6.765Hz resonance frequency. This falls way below the acceptable 8Hz cutoff. I would appreciate any comments from P9 owners or any analog experts out there, since my calculations might be wrong.
Thx in advance,
Hi. Maybe this will be of some help to you . I have a moth Rega- 301 tonearm I am using a Denon Anniversary 103 cart, a Denon DL-304 and a Denon DL-S1 cart with this arn. I am using a aftermarket VTA adjuster. I am not having any problems with these cartridges. You can find the specs for these carts to compair with the AT cart from Needle Doctor which I am sure you know about, hope this might help.David