Why not jCo version 3.0?
We studied jCo version 3.0 when it was released and found there were technical changes but no functional benefits. The end results are the same whether you use 2.1.8 or 3.0: the same BAPIs and RFCs are exposed. However the internal Java code was significantly different which would have required us to port CF2SAP for no evident benefit. So long as SAP supports 2.1.8 we see no reason to move to 3.0.