What a brilliant site!
I don't know anything about the site, but I looked at Dudley Drive because I know three lots of people who live or have lived in Dudley Drive. The street is made up of tenements, and each close has two flats on each of four floors, so at any given number in Dudley Drive there will normally be eight households.
On the web site there is sometimes more than one occupant listed at an address, for example at No 8 James Faulds, J C Gordon and Thos Robertson are all listed as occupants from 1901 to 1904, and at No 10 Thos Davidson, Archibald Fraser and Wm Spence overlap between 1902 and 1905. So in each case there would have been up to five more heads of household living at each of these addresses.
Noting also that most of the names listed are male, with occupations, makes me think that this is from trade directories.
Further, the valuation rolls normally give at least a full first name, so for example J C Gordon would be listed as John C Gordon or James C Gordon or Joseph C Gordon or whatever his first given name was rather than J C Gordon. In the trade or street directories he would choose how to have his name included.
So potentially a very handy resource, but just because it doesn't list someone at a particular address doesn't rule out the possibility that they were in fact there.
I think the facility to see what various streets' previous and current names were, and also to see where addresses are not quite they seemed, is very useful indeed. Have a look at Ann Street to see a good example of this.
