These two should be ready for animation/posing, not sure what's involved with modding but they'll probably work for that too. The two with cloth physics are still under construction, I'll upload them when I can.
Feel free to share, edit, or generally do whatever you want with these.
The heavy's visor is controlled with a shape key, as is the charge indicator on his jet pack. Textures should be packed. Weapons not included.
EDIT: Updated with the default SEAF soldier. It has both a mask and a face model, both of which can be toggled in the outliner.
EDIT 2: Updated with the bionic trooper.
EDIT 3: Updated with the triage medic and trencher.