I have a small industry specific website (about 6000 companies in the industry worldwide). My original site provides info to people in the industry and I have categorized listings of every company divided by subcategories and regions such as New Zealand, Florida, etc.

I pay for the site by selling premium listings and by 'pay for the site' I mean not much more than my hosting and a dinner out once a week.

Customer's have asked for listing (directory) sites outside the main site so I've been creating www.example-australia.com and www.example-europe.com, etc. There are about 15 total.

I intended to put them on regional servers based on where the companies are located but they will all be in English.

Using PHP, they are ALL actually the same code with one 'parent' site in each region then each other site on that server will be an add-on domain using an index.php file that just has an include() to the parent. Also, all 15 are linked to each other.

(I know - there's a lot of background here)

My question is; is it more or less worth the work to have the different domain names and to be hosted in the different regions if the sites are still all in English AND the sites, from a spider's view, all look the same? Also, they are all linked to each other.

Any opinions are greatly appreciated!