Caching with geocopy enable on a three site or larger federation?

I have seen that, in the pre-geocopy version of ECS, 10%-15% of the total storage space is reserved for caching.  If we use geocopy then I don't see the need for such a large cache as we would only need to cache reads for objects that have not yet been synched across the multiple sites.  For most reads we should only need to check the metadata on on the owner to ensure that the local copy is the latest.  How much cache do we have on geocopy enabled systems?  Thanks.