According to the Daily Mirror
"A military source said: “These helicopters are extremely agile and quick - with the ability to get into smaller spaces, travel in-between high buildings with relative silence and at speed, with eight soldiers."
Relative Silence?? Well, they must be some vastly modified Dauphin's. I've never heard anything make a noise like a 365. You can feel the air vibrating for about 8 miles as its heading towards you and then the wailing banshee noise of that fenestron.
Speed - Yes.
Agression - Perhaps
Surprise - Erm, well perhaps not!