The XR4x4 has a wider track dan the cossie 4x4. When fitting alloy wheels to an XR4x4 the wheels stick out the arches quite quickly. I don't think you will be able to fit escos wheels to an XR4x4.

What is more interesting is that the cossie hubs will give a higher roll centre than the XR hubs. You can easily tell that from the locations where the steering arm and TCA connect. So for a handling point of view I'd definately want the cossie hubs over the XR hubs.