Should I or shouldn't I?

[Fiddlebog]

Get it done. Yes, the dual-row bearings are much less likely to fail. And depending on the history of your car (has it been run consistently without long storage periods? has it been maintained regularly?) it may not be an issue that ever has a real chance of arising.
However, once you have the transmission out, the rest of the labor/parts for the IMSB swap is not all that much.
Additionally, if you ever sell your Porsche, we all know the first question any buyer is going to ask.