From purely technical viewpoint, most important question to ask is: how many links (between processes and external) has your present enterprise model? The second and closely related question is: do you have a tool in place to automate migration?
Being experts specifically in process migration, we have evidenced enormous efforts, which companies spend when doing such migrations practically. While there are relatively easy ways to move individual processes in some most popular notations, such as BPMN, there still exist significant problems in moving underlying business semantics between different process engines. It is not a problem (or, at least, not a big problem) to move manually a single process by mere re-drawing it in a cloud tool borrowing from an existing diagram in another tool. However, if you have to move an average enterprise model of 100,000+ diagrams, it grows to an immense labor and cost, which is simply impossible without a sort of automation.
Complexity of migration directly relates to model topology. When you have a single process not linked with other processes, you can move and then test run it individually. When you have hundredths of closely interconnected processes, the complexity of their migration grows at least exponentially with a number of links and further complicated with inability to evaluate processes individually until the whole enterprise model has been properly moved. Presence of automated migration tools, an expert team experienced specifically in such migration task and detailed plan for migration are essential for success of such challenging mission.