"Do you prefer a combined PSK/FAK or carry the 2 seperate?"

Both, sort of.

My PSK includes the stuff I might need for first aid in an emergency. It is relatively complete, this way, on its own. Many of the items can have either a first aid purpose or other emergency wilderness survival purpose, depending on what i need and how I use them. For example, the triple antibiotic ointment has first aid uses, but can also be used as petroleum jelly to help start a fire.

But nothing in my PSK gets used unless it is a real emergency, so that nothing is used up or worn out when I need it. So, I have a separate first aid kit, which gets used for normal first aid needs.