I have it on very good authority that the SAS styli are more than just "replacements" for the originals, as the Ed Saunders ones are (his V15 III stylus is all but identical sonically to the originals I'm told by someone who's compared them - he didn't like the SAS at all and I don't think it was because of setup either.........).
The V15 III does seem to depend rather a lot on the diamond and its finish (unless Shure did other suspension changes and didn't tell anyone). The HE and I believe the MR versions sounding far more spacious and all but sweet toned in comparison with the forthright, precise and slightly ungracious tones of the original VN35e in my experience.
As to the V15 IV series. This model removed the loading sensitivity of the earlier models, but seemed to cods-up the sound in the process. Extended listening shows it's all there, but not at all charming to listen through in some systems. Other cartridges of various types seem to expand on the basic presentation of the IVHE rather too much, and this includes all the other V15 series IMO and my example DOES have a good and little used stylus too...
The G version retains the compliance of the HE I believe, but it's only the diamond profile that's different. Give it a go and see what you think..... Recent discussions about certain classic ADC's show what and how the playback compromises can be jiggles to get a basically accurate playback, but with far more grace and charm (not really added colourations if you get my drift) to make playback so enjoyable. I keep a good original V15 III as a reality check, but for pure enjoyment from a vintage cartridge, one or other of my ADC's or the Sonus Blue gets fitted, as they're far more satisfying long-term.
Tear down these walls; Cut the ties that held me
Crying out at the top of my voice; Tell me now if you can hear me