"And with gas you're always depending on the wind.
Not with spray, cause you can use it at a shorter distance."
The spray is nothing less dependent on weather:-(( The fog type is even much more affected.
"You're right with one point:
A gun (even a lookalike), can stop an attacker just by showing it or with firing a blank in the air."
You say "CAN", I say MOST probably WILL stop the attack. All of the international statistics show this evidence.
"There is no way for perfect self defense."
Actually a 12 ga shotgun IS perfect way for home defence and a .357 Magnum snubbie for carry. But not so easy to get these in our old continent in the law abiding way.
"But with spray you're at least not in danger of ending up in jail with accidential manslaughter."
Have you got even ONE, DOCUMENTED case, when someone killed the attacker _accidentaly_ with a gas-alarm gun in a justified selfdefence situation?
I think it is only a speculation.