The 5 point Chain Rifle toting variety is the best option in my opinion. A Chain Rifle makes the BS-11 irrelevant. It uses the large tear drop template and allows an Intuitive Attack making this a nightmare for Camouflaged or TO Camouflaged or even enemy in Zero Visibility Zones without even needing to Discover the enemy first. The Kuang Shi WIP-13 will help with the Intuitive Attack and then the large template will reach out and touch the enemy pretty regularly.
It sounds nice to be able to blow up when the trooper goes unconscious but I've seldom seen a Kuang Shi make it close enough to enemy troops to take advantage of that. However, if you have an enemy that is aggressive about moving forward you might find it a handy feature.
Being able to go V: Dogged after a wound is a convenient way of getting a chance to reach the enemy for another shot or two with the Chain Rifle.
Given that the Kuang Shi is Extremely Impetuous they cannot benefit from Partial Cover MODs. The PH-12 gives the trooper a little better chance to dodge than the Zhanshi or Celestial Guard but it might be difficult to make it to a position of value.
One of the strong values of a Kuang Shi is the fact that they generate 2 orders. The Impetuous order requires that the trooper move towards the nearest enemy figure (not a token) so it is possible to lead them around the field by careful positioning of a trooper. If they don't like the direction you are drawing them in they may just cancel the order but it will cost them the regular order as well.
Because the Kuang Shi are impetuous their movement is somewhat predictable. Be sure to place them where you can keep them alive long enough to reach the enemy. You might find it necessary to skip their Impetuous order (which will cost their Regular order) to keep them safe until the right moment. However, if you need help flushing out a camouflage marker enemy the Kuang Shi are the right price for cannon fodder.
Active Turn Role
I like to keep my Kuang Shi looking for infiltrators so I keep one or two of them watching my back for the first turn or two. They can use their Intuitive Attack to strike at those assassins before they reveal themselves and possibly put down the assault before it happens.