I take it they are since they are pretty much just ISO files, anyone know for sure?

Why? Let me take you back a year or so...

*Guilty Gear X2#Reload is added to backwards compatibility.
*GGX2 seems to not work in EU
*GGX2 removed from EU BC list
*GGX2 announced as comming to XBLA with Spyro on 16th June.
*June 16th comes and only Spyro shows up in EU marketplace and the dvd version of GGX2 still dosnt work.
*Mr Eibmoz weeps.

Do you not want my money MS? :(

If the game was coded to be region locked then it is region locked, simple! Microsoft does not modify the code of the original game in any way.

Originals are mainly a joke anyways. $15 for games you can find in the store or online for anywhere from $1 - $10 or so. I mean I got Crimson Skies for 37 cents.

Create a new profile (if you haven't wasted the 3 times gold subscription) with a US address. You'll be able to get it then, although you'll have to log into that profile to use it.

I've done it before to get ahold of things off the japanese Marketplace, which last time I looked was horribly pitiful :(

Some of the games in the program are actually much cheaper then their disc counterparts, I mean I see Xbox games above $15 at eb games and other used game shops regularly.

But the disk version dosnt work either (in EU) :P Besides, I want GG on my HD to play whenever I get a notion without faffing about with disks.

You just answered your own question Mr Eibmoz :)