Hi alla_next Damien,
Just to add a little comment to Salva's response and to your last reply.
Yes, you are correct, there may be many users wanting the solution. However, we are not looking to build a quick plugin features as what we are creating here is a complex and full business solution. Before we introduce the multicurrency solution, there are many other things I want and need to release. There are parts of ATUM that have to be done before others.
As a creator of ATUM, I want users to be able to manage their inventory without effort introducing, advanced purchase ordering, automated warehouse management, inventory planning and most importantly a mobile app to handle all this on the go and more.
PS: as you mentioned above, you have to run two websites. Even though I do not happily point to 3rd parties, there are solutions that are web-based and able to connect to both of your stores to sync stock. You can run things from the web environment.