You should modify the shotgun to either knock the victim back a fair distance or tumble the player and send him flying a short distance.
Disabling players from moving is an ability that is not fair if there is only one infiltrator. The inf CAN disable a player from moving at a close range with a finger trap thats thrown like a spear, but that is to help with 1v1 combat.
We've made some changes to the formula;
All guns are a lot more powerful, around 65%
Health of infiltrator is reduced to 150hp from 300(what was i thinking)
Changed the infiltrator's main arm to an MP5SD3.
Gave the infiltrator a HE grenade. A single HE grenade.
This means that the inf must use stealth to track down the guards and eleminate them. Be silent, take your time, and don't go rambo. Being able to take down an enemy in a 1v1 conflict is entirely based on the skill of the guard, your skill and the ability to use the Finger Trap.
these changes are free to change at any time, depending on feedback in server and on forum.