Do LI HM with columi is not overgearing it.
As i recall, the first few times I did HM LI, I had a couple pieces of Tionese on, and I think I was able to replace my leg armor, mainhand and chest within a few runs. This was while still learning the place with the group, as it was a new FP. You assume that everyone has farmed all of the T1 HMs for all their Columi before ever setting foot in HM LI. I did not. Several people that i know have not. I did HM LI yesterday with 2 people that needed items from HM LI, and not just the Rakata. They were decent players that had done the place maybe twice before, and they were rewarded for their skill.
Totally different bosses and tactics, that's not practice.
That is why you fail. - Yoda
Learning to respond to mechanics IS great practice. Maybe they're not the exact same mechanics, but you learn to RESPOND to the many "move out of this" mechanics, the interrupt mechanics, and the "do this or die" mechanics.