This is a cool idea. There's currently no point in using the silenced pistol over the colt 45 but this would give it an advantage which I like. I definitely think not showing the 'x killed y' message is a good idea and very easy to implement. I'm not really sure removing the wanted level from it is wise though. What would the criteria be for getting a wanted level? How am I supposed to 'detect' if the victim can 'see' you?
EDIT:
Turns out the silenced pistol already has an advantage I just noticed..
The distance from a player you have to be for the 'Shooting in public' crime is reduced from 150m to 40m.
I'll reduce it to 30 and remove the killfeed for now. I'll leave the wanted stars though.