Multi-X

I´m gonna buy a Dreamcast... If I buy one with a Multi-X chip can I still play backup games?
And will I need a Multi-X chip too play the JAP and US versions(since I live in europe)??? I ask this because I´ve seen the patches here on DCcopyworld...
I would really like an answer to these questions before I buy one, cause the Multi-X version is much more expensive...
Thanks.../NaNNoK