[gainsy]

Personally never had a problem with cf, never snapped any but know it has been done, especially to the upper chassis's, there are various ways to make it flex more but that involves cutting parts of the carbon fibre away, there is a thread in the associated section on flexing
The front shock mounts are 3mm thick standard, my car has had a upgrade to 4mm, i agree the 3mm version does feel fragile but should be plenty strong enough really, although the 4mm version on my car does feel really solid & it survived a full speed barrel roll the other day when i was expecting it to disintegrate
My rear one is 4mm as well
I have heard of people glueing 2 together for extra strength but i would think 6mm is a bit much really
Never had alloy shock mounts but i expect the worst you could do to them is bend them, remember breaking plenty of plastic one's
Pics of my shock mounts below, dunno where they came from but i could always ask the guy i got the car off for you