Honestly, the damage/penetration details aren't too important (subject to balance) - but the unit unique features (cannot shoot after moving; cannot be seen unless enemy is adjacent) are important.

I'd really like to see another infantry unit or two for the guardsmen.

My suggestion for that would be a ratling sniper/scout unit:

* 3 ratlings in a unit
* 8 dmg 6 pen (x3 due to 3 ratlings)
* range 3
* sight 3
* 83% accuracy (or higher)
* cannot shoot after moving
* cannot be seen unless enemy ...