A fair, reasonable, and refreshingly unhysterical reaction to what are undoubtedly elements that are problematic for a modern audience.

I'm a huge Holmes fan, but generally I prefer the short stories to the novels (with the notable exception of The Hound of the Baskervilles, which feels slightly like a spin-off from crime fiction into gothic horror). Despite the issues with The Sign of Four that you mention here, I actually think on the whole the Holmes canon is quite progressive for it's time.

For example, in The Abbey Grange, Holmes is shown to have genuine compassion for women trapped in abusive marriages (and indeed, that story could be read as an inherent critique about the fact that under Victorian law, beating your wife was permissable provided you didn't use a stick that was greater than a certain thickness).

Conversely, Steven Moffat's take on A Scandal in Bohemia had Irene Adler need to be rescued by Holmes in the finale, and also sexualised the character in a way that felt unnecessary to my mind (making her a dominatrix). A lot less progressive than Doyle's original version, ironically.