To My prior project experience, Orchestration very depends on the Server Request manuplation. but even if it provides the custom service request made in Groovy, it still has some limit on flexibility, and the perforamnce is also you have to consider about Json. For example, do the same PO receipt for couples of lines,, BSSV&BSFN will be more ideally than JSON in response according to our testing. Besides Orchestration counts on JAS front end design, it is for high level solution, Whereas , BSFN is for the lowest level development, which can provide much lower level transaction control in. Orchestration of course has advantage on the fast implementation ,So that is all you need to consider.