Entirely up to you. If you want to move apps from your old phone to the new one with Titanium Backup you may want to use the temp root. You may also want to wait until there is a perm root so you’re just doing things once. You may also want to wait until a ROM comes out or until ICS.

If there is a perm root before ICS comes out, it is highly likely that you will have to unroot to get the ICS update.