I've got all three mounts installed.
Vibration is particularly bad when the weather is hot (we've had high 30s, and early 40s in Melbourne, this summer), and, even when it's cool, the steering wheel vibrates on idle, and the rear view mirror can be very blurred.
However, why on earth anyone would say "this is too much for everyday driving" is a complete mystery to me. I mean, what about the Clio's rock hard suspension (mine's a 200 Cup Trophee), noisy engine, notchy gearbox, and nasty plastic interior?
I am HAPPY that this car is less civilised than ever. If I wanted a smooth, quiet, comfy ride, I'd drive a Lexus.
Since I had the Powerflex engine mounts installed, my car is easier to live with than before... because it's even less like a boring Lexus.