I have an internaxx account. The service is very professional and I haven't had any trouble, not that I do anything fancy.
Hi
offshore CFDs - Try Investors Europe
The biggest gripes I have problems I have are is that to transfer money you will need a swift transfer (25 pounds) & they charge 0.2% fees per annum.
I had trouble getting quotes for some of the more esoteric instruments - eg split caps, convertibles etc, but they said if they don't work online they can do it over the phone.
As for offshore CFDs, all I know is that IG Index has an Australian brance, and there was a South African company around & maybe Jamaica? Check with the other boards.
Its great going offshore, but there is the problem that you never know if you can trust that small company you've never heard of that is regulated by some govt agency you have no idea about.
Good luck.