One of the benefits (not usually mentioned) of these LCR meters is the lower Z ranges, like DCR at 1 Ohm and ACR 3 Ohm ranges, where the DUT current can be as high as ~67ma. These ranges are below most quality DMMs like the KS34465A (100 ohms) and DMM6500 (10 ohms).
That statement may not be true as the 6.5 digit DMMs you mention have a lot higher accuracy compared to an LCR meter and you might be operating the LCR meter outside the range where it is most accurate when measuring low resistance values.
Well it is true regarding the KS34465A vs Hioki IM3536 measuring below 100 milli-ohms, the KS spec per performance verification is an error within 4 milli-ohms after 24 hours, 3 milli-ohms within 24 hours on the lowest 100 ohm range. The IM3536 is a worst case 1% error of range at 100 milli-ohm range as base line specification, or 1 milli-ohm max error in 100 milli-ohm range.
The KS is fundamentally a more overall precise instrument for DC resistance measurements, however at the lowest range on the KS is 100 ohms, whereas the lowest range on the IM3536 is 100 miili-ohms, a thousand fold lower full range. One reason we acquired the Keithley DMM6500 was for the lower 10 ohm range, also the TH2830 has a 3 ohm DCR Range.
We haven't done much low resistance comparisons, but did find a note from 10/15/21 where we compared the TH2830 with the newly acquired DMM6500 and the KS34465A (didn't have the IM3536 then). The resistor was a Vishay 0.12 ohm that measured 0.120560, 0.12056 and 0.1197 ohms on the TH2830, DMM6500 and KS34465A respectively.
Anyway, for very low ohms measurements where the LCR meter utilize a much higher test current (KS uses just 1ma) and a much lower full scale range, we'll lean towards the LCR readings if the measurements differ much between the DMMs and LCR readings.
Of course the type and use of the precision Kelvin clips likely has more user induced error than the instruments themselves at these low R ranges
BTW one shouldn't discount these modern bench type LCR meters regarding overall accuracy and ability to resolve small impedances. Likely they employ the modern single chip SD 24 bit ADCs, like some of the newer DMMs do, which are quite remarkable in achieving performance levels usually attributed to more complicated and costly full circuit designs.
Best,
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