Research Supporting Multiple Country Domains?

[Fruit & Veg]

I have a client who has multiple sites for multiple countries all hosted on the particular country domain, widget.co.uk, widget.fr, etc, etc.

They are proposing removing all these domains and placing a mega site on one new domain to cater for all markets.

Yes, I'm horrified too!

I've told them no, don't do it. I've given various reasons but they have requested third party research to support these reasons. Can anyone point me in the right direction of reports, research or articles that support the idea that multiple domains for multiple countries is a good idea?

Saying that ebay, amazon, google, etc all do it is not good enough.