Hi Nico,
Of course it's recommended to have the B1i version aligned with the B1 version (taken from the same B1 installation/upgrade package.
In general B1i and B1 taken from different versions are compatible. But please be aware if you are planning to use standard integration content like the sap.mobile scenario or others you need to test them for your specific B1 - B1i combination, first.
Please see SAP Note 2129512 - Integration framework allows cross-SAP Business One version installation.
Best regards
Bastian