I have had my '01 S since new. When the IMS issue came out I was very concerned. Over the years I have had conversations with three top notch independent Porsche mechanics in the Los Angeles area. One said to do it for peace of mind. The other two said to not worry about it that there were other issues with the motors that could cause them to fail besides the IMS.
All three recommended changing the oil regularly and examining the oil filter for metal pieces. I take it a step further and send the oil to Blackstone Lab (
Blackstone Labs) for analysis.