Until recently I was fortunate to be able to listen to a Model 20/12 with a Series V Arm.
I am assuming there will be a family sound from the TT's, and the Model 20, Model 30 and 60 if used side by side with the same Base Support Structure, Tonearm and Cart' would sing out the SME Sonic Trait, where the design for each might show the division that comes between them, or maybe not and my assumptions are very wrong.
Many years past, my assessment of the Series V in comparison to the IV, did not offer the impression the V was much more advanced in how the presentation was perceived to the Series IV. The outcome being my ears were the Judge and I bought a IV and still own a IV still to this day, even though it is rarely used at present.