regarding user exits

Dear experts,

In SD module, After creating sales order and shipment Process, i want to save the sales order datas including shipment number datas into ADDON table.

Timing wise, Storing sales datas into ADDONTABLE must be done only after the shipment process. so i think i want to use user exits in shiping screen , using which i can save data to table.

Pls guide me whether my way of doing is correct or not.

my friends says User exits does not support in future so better not to use it..if so how to do with alternative.

pls guide me.

ambichan