if you see that the system still cater your companies needs then stick with it. there are lots of big companies including banks and until now they are still using the old school but manage to compete. in case you are planning to migrate i think the best thing to do is refer it first to the top management because it involves a lot of money. one example is your database alone. if you are going to migrate to Oracle then you must risk the huge amount your company will be spending. and another example is the staffing. you must have additional test team to make sure that you have a quality system considering that your current systems developer are using the old school then there is a greater risk that they are still on the stage of trial and error with the newer PL tool. as you can see there are lots of factors to consider that also considerably affect the ROI.