Why a slicer/sniper? I think that dilutes the Sniper concept too much ... IMO.
In real-life Armies, this is what the TO&E looks like (for the US Army; note the USMC has a very different set up):
Fire Team
1 Sergeant (probably Soldier/Noble)
1 Light Machine Gunner (Soldier, high Strength)
1 Grenadier (Soldier, probably high Strength)
1 Rifleman/Radioman (Soldier)
In rank order (from highest to lowest).
Two fire teams, called a squad, have a staff sergeant in command (higher level sergeant). Two to four squads, called a platoon, are led by a lieutenant (Noble/Soldier) and a platoon sergeant. Note that the lieutenant is lower level than the platoon sergeant and probably lower level than the staff sergeants... if there's some kind of Plan talent, the lieutenant should build towards that.
In addition to the TO&E "mandated" stuff mentioned above, often a platoon will have a heavy machine gun team, a "marksman" (not a sniper!) and other special troops attached.
Mercenaries or special forces teams can be smaller and/or more specialized. (For instance, a merc team might have a dedicated martial artist, whereas a martial artist in the regular army basically does martial arts in his spare time ... even if he's better at kicking arse than shooting stuff.)
Special Forces teams vary widely. This is based somewhat loosely on a US Army Rangers team. There's more "room" to build a special forces team the way you want. Note that in real life special forces teams tend to be large. Fortunately, splitting them in half is common practice (a team of five or six special stormtroopers should be easy to manage in combat).
Officer (Captain or Major)
Team Sergeant (2-i-C; often trained in intelligence, sometimes this person is a lieutenant instead). If the Team Sergeant is in fact enlisted, they're almost certainly higher level than the Officer (as they're older and more experienced).
If the team splits in two, the officer leads one half, the team sergeant leads the other half.
Two each of:
Intelligence - trained in linguistics, interrogation, analysis and "making friends in foreign countries". Give them lots of Gather Information and have them get info on the enemy before the attack.
Medic - literally trained in trauma rooms in big cities where shooting victims are common. They have the Surgery feat.
Engineer - the "Smart Hero" of the bunch, though capable of killing someone with the very tools they use to build stuff. Trained in construction, battlefield fortifications, demolitions and possibly things like computer hacking, disabling devices, and what not.
Communications - capable of building a radio from scratch, carry the heaviest load.
"Weapons" - the killers of the team, they're trained in heavy weapons and melee (unarmed and various melee weapons).
Note that this messed with the CR/Challenge Code/whatever it's called, as only the "Weapons Guys" and the two leaders are actually all that great at combat and direct combat support.
There's two of each role for redundancy. It sucks when your only medic gets shot (which I swear happens in every novel of this type that I read; authors don't know medicine).
