Split it down the middle in my opinion.

Negative faction sympathy AND neutral/enemy faction and the guards attack you.

Allied faction they warn you first and then attack you.

Own faction does not attack you.

Red SL - Copbots attack you on sight like NC1 copbots used to. Not the carebear ones today.

If you kill someone you get sympathy in your faction if they are enemy to you. If they are neutral you gain nothing. If they are allied you take a faction hit with their faction standing.

Gaining SL should be done automatically and slowly past -50 up to +10. After that it should be missions. -99 to -50 should be regained by killing enemy runners or people with shit soullight themselves.

This way if you had bad SL and your opponent did too (due to a clan war of some kind) then you would stand a chance of getting some reward eventually for killing them even though initially you would still be branded a murderer (as you committed a crime technically).

It would also allow the "RED SL" guys to work their SL off in their own HQ if their own guards didnt attack them.