My Quantum uses the Sierra column and is secured at the cockpit end, so it will do all it's collapsing before stressing / breaking it's mount.

I seem to recall that my Caterham wasn't secured at the cockpit end, so would only collapse when the steering wheel made contact with the driver!

Have I got this right, or am I forgetting something somewhere?

Isnt the collapsing part to prevent the steering column getting pushed into the driver in event of a front end crash pushing the steering rack back??

Personally i'd want the bit just behind the dash fixed exactly where it is very securely

The safety design of the Sierra system includes the original wheel. It's designed to collapse at both ends - the inner column collapses inside the outer to prevent it pushing into the driver and the wheel has shock absorbing properties too. That's why if you use a Sierra column and a non OE wheel you must fit a collapsible boss.