WipeOut Pure and MP regioning

Hi all!

I thought I'd ask here because I've been trying to find some information on this and can't. I know WP comes out in the US now before the UK (I knew that the announcment we'd have it first was too good to be true), and I know that the reason that multiplayer between Japanese/US/Europe games doesn't work mainly due to language and menu differences, but...

Does anyone know if this is purely a Jap/RestOfWorld thing, or it really does matter between the three main launch regions? If I import a copy of WP from the US, is it likely to work multiplayer with a European copy when it comes out approx. 6 weeks later as the menus, I assume, will be pretty similar? I'm curious because I'm a massive WipeOut fan and it was one of the reasons I bought a PSP in the first place. The only real reason I could imagine this being different is the content downloads...

Cheers.