My impression is that in recent times, the number of WP admins has grown roughly in line with the number of WP pages. This has nothing much to do with the activities of certain high-profile sysops, I think. Nor is it directly related to the presence on the site of a handful (at any one time) of problematic users. I would say a sysop per 1000 or more pages on the site is not excessive. Sysop powers of rollback help in dealing with nuisance- or graffiti-level vandalism. The power to temp-ban IP-only users is also useful in repelling the casual vandal (of the school kid/Random page add rude word type). The more talk pages, the more need to have a little supervision of talk discussion when it gets heated. I honestly think those things, together with quick deletions of low-grade pages, represent the bulk of sysop activity. I would argue that the volume effect of the growth of WP means that the sysop body does need to grow in line. Actually my impression is that the time to discovery of casual vandalism is lengthening, on average. I'm no great fan of a self-aware attitude amongst sysops; it can be helpful in dealing with certain users to 'wear the hat' rather conspicuously, but that trick doesn't always work. I thought that it was interesting that Jimbo, in his London talk, was in agreement with Theresa Knott that vandalism as we presently know it is not too serious an issue for WP; a comment that he balanced by saying (in effect) the Old Bolsheviks of the site were more of a problem. Charles