I'm not the best person to give you advice on a Rakkan line-up. But if I were to main a Rakkan, I would use All Silver turtle front line + All Gold/Silver crossbowmen at the back.
All silver turtle front is a bad option for most battles. While they each have high health, a squad of smaller units have a combined higher HP. And of cause, they take up half the battle field, and do little damage to large units.
I never found a use for samurai, other than to use in quests vs skeletons when there were no spiders. But I didn't do much PvP on the ptr.
I suggested a PvP line up and the point is, making the turtles as bait/tank while keeping the backline stable, I never mentioned they were for DPS. If you will focus on pure humanoid units, you're an easy prey to any Lich. The majority of your damage will come from hero skills/spells and crossbow units + pierce.
As a Lich player, that's one thing to be scared of. If you will go pure humanoids against me as Rakkan, you will melt in seconds.
In addition, you can always mix and match them. I never said it was the best line up, I was only giving my personal preference. If you have one you should share it as well.