Presumably smaller signal strength = smaller moving parts = more delicate control/refinement of movement/signal, presumably 0.2mv a speck 'better'.
BUT
Watch your 'resultant' impedance as well as your signal strength.
IF your SUT does not have individual adjustable settings (most do not),
the gain in db (X factor) will control the 'resultant' impedance shown to the phono stage.
the formula for recommended 'resultant' impedance (after gain by SUT)
formula = coil impedance x 10. a bit less than or more than, just use it as a guide.
both mentioned cartridges are 12 ohms
guidance: 12 ohms x 10 = 120 ohms 'resultant impedance' guidance
find an X factor (calculate XF squared) that will result in the recommended impedance 'shown by your SUT' to the phono stage which is typically 47k ohms (confirm yours).
47,000 divided by X factor squared = 'resultant' impedance
then, see what signal strength will result from that x factor, enough? too much, overload?
i.e. one of my SUT's four X Factor options: 10 ohm input is x factor 20.68 (+26db) (x factor squared is 428). phono stage 47,000 divided by 428 = resultant impedance 110 ohms. just under guidance
it's 30 ohm input is X Factor 18.27 (+25db) (x factor squared is 333) phono stage 47,000 divided by 333 is 141 ohms, just over guidance
now check your signal strength using the X factors that get you close to the guidance of 120 ohms
stronger cartridge 0.5mv x X factor 20.68 = 10.34 mv. allow some loss, say 9.5 mv, 110 ohms.
0.5 x X factor 18.27 = 9.14, allow some loss, say 8.5 mv., 141 ohms. I would use that setting.
lower 0.2mv signal,
0.2 x x factor 20.68 = 4.14, allow some loss, say 4.0 mv, 110 ohms
0.2 x X factor 18,27 = 3.65 allow some loss around 3.5 mv, 141 ohms.
My SUT, I would chose the 0.5mv version.
You probable should consider a SUT with individual adjustments for gain and impedance.