Are cheap AD584 units worth it?

[dorkshoei]

So here are my measurements, however not as official as guy48065 has done with one hour warmin etc. just power up two Keithley 2000 not calibrated for at least 8 years but that's all I have here 
The K-unit figures are pretty spot on, the L-unit figures are fiction.

I'm seeing a few units advertised with an ad584-m.   Does anyone know about this variant?

"Built-in AD584-M, highest accuracy and stability."

https://www.ebay.com/itm/KKMOON-Accuracy-Voltage-Reference-Module-4-Channel-2-5V-7-5V-5V-10-Hot-Q3D9-/254629183828?_trksid=p2349624.m46890.l49292

[magic]

Rev. A datasheet lists -55-125°C temperature grades as S and T, with specs similar to J and K, respectively.

M grade is probably fake. The photographs you linked show the K grade, by the way.

[jharris1993]

NOISE FILTERING
The bandwidth of the output amplifier in the AD584 can be
reduced to filter output noise. A capacitor ranging between 0.01 µF
and 0.1 µF connected between the CAP and VBG terminals further
reduces the wideband and feedthrough noise in the output of
the AD584, as shown in Figure 9 and Figure 10. However, this
tends to increase the turn-on settling time of the device; therefore,
allow for ample warm-up time.

This is the relevant section of the Analog Devices datasheet.