Which Spindle Encoder

I'm trying to determine which is the best spindle encoder to use.

I already have an Omron E6B2-CWZ1X @2000 P/R. The documentation for which, shows a maximum response frequency of 100kHz.

I am using a Mesa 7i76e connected to a Raspberry Pi 4 with LinuxCNC installed following John Thornton's instructions.

I'm hoping for a maximum spindle speed 2400 rpm.

For example, based on 2400 rpm, and what I have gathered from other threads here: 40 rpm x 8000 ppr = 320kHz.

Do I assume a quadrature count per revolution when using this equation?
If so, at a max frequency response rating of 100kHz, does that mean that the encoder can't keep up?
Are there other bottlenecks that I need to watch out for?

Thanks for helping me out.

-Loren

According to the data sheet
3. The maximum electrical response speed is determined by the resolution and maximum response frequency as follows:
Maximum electrical response speed (rpm) = (Max Response Frequency / Resolution) x 60

This is found at the bottom of page 2:

Hopefully this is the correct data sheet:
www.farnell.com/datasheets/2693580.pdf

According to the data sheet
3. The maximum electrical response speed is determined by the resolution and maximum response frequency as follows:
Maximum electrical response speed (rpm) = (Max Response Frequency / Resolution) x 60

This is found at the bottom of page 2:

Hopefully this is the correct data sheet:
www.farnell.com/datasheets/2693580.pdf

(100,000 / 2000) * 60 = maximum 3000 rpm

I hope I have this right.

Thank you