I was thinking about emulating Rep in Fate recently, and I came up with a new idea. Characters need a Networking skill, a Rep stress track, and ~3 Rep ranks that they can divide between 1 or more Rep networks.
Whenever they ask for a favor from a rep network, roll Networking against the cost of the favor plus the total number of favors they've asked from their network during the session the exceeds their rep rank in that network. Rep rank is equal to the number of favors you can ask for without penalty. So a character with 3 Rep in a single network could ask for 3 favors without penalty, then would add +1, +2, +3, etc for each additional favor after that.
Failing the roll would still get the favor, but would take Rep stress equal to the failed shifts. Rep stress would only clear at Significant milestones or at the end of a session as long as the character has not asked for any favors that session.
Additionally you could use multiple rep ranks on a single favor for a bonus, so, for example, you could use up 2 favors for a +1 on a single favor.
There is a little bit of bookkeeping in keeping track of rep stress and how many favors the character has asked of each rep network, but I don't think it would be too hard to track. It helps differentiate players so that a player with a low Networking but high rep might be a better in some cases then a character with just a high Networking, but the high Networking character will be better at asking for more favors overall. Any feedback?