I tend to develop them as the game goes on. At the beginning the players usually just need "someone to pick that lock" or "someone who'll guard our back for money" and they have very minimal stats (like profession, race, level. I look skill bonuses up in character law according to their level).
If they survive and stick to the group long enough to become of some importance, I fully stat them.
After re-playing d&d (b/x) for a while, I found that Morale is actually a nice way to handle their reactions to danger: it lets me be completely impartial and makes running NPCs slightly more entertaining (sometimes they'll surprise you, they really seem to act according to their own will, rather than being controlled by the GM).
I'm thinking of incorporating it into RM, too, maybe just as a straight % roll.