Sherlock is treading a line between retaining the spirit of the source material and updating the setting; it is not a modern police show with modern sensibilities, it is a Victorian thriller set against the backdrop of modern London. Murderous Chinese acrobats are a plot device consistent with the Victorian milieu, and I would suggest that this period aspect was made explicit in as much as that the gangsters were identified as Tongs, as one might expect in a Victorian novel, rather than as Triads, a more current criminal threat.
For what it is worth I find this treatment of Holmes more engaging than yet another lazy period adaptation; to my mind the original works were interpreted with Jermey Brett.
