Hi,
SAPSetData works well for us in AO2.3 BW 7.5.
I'm not sure I understood why you want to remove the Crosstab. Do you want to replace SAPGetData with SAPSetData?
We put SAPSetDATA in a separate tab of same Workbook.We writing back to a cube, but I don't think it makes a big difference for SAPSetData.