The only real complaint I have with the -100 is that it seemingly makes there no punishment to killing someone in town. (Just got minigunned point blank in ncr and he walked out of town then walked back in to try and get the gear. Crowd got the gear - they were like vultures. Combat armor does that to people I guess.)
Because we don't want to have "faction hopping".
If you wan a way to rise it for those that got it lowered by crafting or accidents then make a bribe/donation system where player can pay to reduce his negative carma in one of the main cities - the cost should be geometric in growth the more negative rep player has.
The big factions have enough money anyway. So they could abuse it even more.
the reputation decay thign needs to be remove - it will only result in massive jump in PK ing in "safe areas" and expecially where guards are weak.
Did I say 10? Lies! It was meant to be 100, no idea what I smoked when writing that. Will fix it right away (will work after next restart).