OSPF Vs EIGRP

Dave do you know of any Global Corporations that are using EIGRP ? IF so, what do they do when a major merger takes place and the corporation aquires a large amount of non Cisco routers throughout their newely aquired global network ? I have also been trying to locate a case study of the percentage of global IP networks currently using OSPF Vs EIGRP and any recent trends towards one or the other ?