As far as LI..the way its been portrayed to me is the boogie man of FP's. I'm in columi and have been told Rakata is needed oddly enough.
rakata is not needed. What is really needed is a well-organized team that knows their class in and out.
outside of that, you need to overgear the environment to compensate for lack of one of the above 2. Which is why peeps recommend Rakata. the instance was designed for columi, but with the above expectations. This is why it's a tier 2 HM.