Funny thing, though, when I they've been sent after me, I've never - not once - seen the message. I know it is probably sent, I just miss it completely because I'm likely too busy being a toolbag! still, whenever the red blips show up, they are far too easy to dispense. If they were able to throw grenades or come in charging, more aggressively, then I'd be more intimidated. As of now, they're more of a light Gang Attack than anything.
As for the idea of a Lamar initiated "drive-by," I think that would be brilliant.
To add, as I mentioned in another thread, I'd also love to see a "Hire Assassin," similar to the mugger but much more deadly and who can follow a player across servers or if the player quits, re-engages (like a bounty) when the player comes back.
Just a thought.