I think regarding scarring, penile inversion uses the full-thickness penile skin to form the neovagina, whereas dr suporn (who did my SRS), dr chett, and others who use "non inversion" use half-thickness scrotal skin which they then score with a machine that not only removes the hair follicles (rendering electrolysis unnecessary) but also sort of makes a bunch of crisscross cuts in it, which lets it stretch to twice the original size, ie you can get a lot more vagina out of a lot less material. As you can imagine, this material needs to be dilated more aggressively, though, while scar tissue forms and then breaks down to ensure no loss of that extra depth/width.