"Any comments on this ?
Car doors are locked by this process but car may not be fully security armed ?"
Most likely.
"Would it be possible, if entry was forced, to drive away as the fob is still in the car ?"
Absolutely
Using the metal key has random effects on my 2014 model.
The alarm will go off if the car is unlocked with the key (formerly locked with the fob), which is very annoying.
A AU$60,000 car and no electrical contact to detect that the mechanical key is used to open it and switch off the alarm. Somebody forcing the lock would still not be able to drive it.
I would like to keep the spare fob at home and give my wife, who doesn't drive, the metal key to put her shopping inside when we are meeting somewhere later.
EDIT:
Sorry I somehow missed there were two more pages and the date of that query is old.
The issue with the alarm going off using the key is still relevant though.