[jaclaz]

>If you are in a higher risk computing environment, it would be logical that you would sign out of your account after you've finished using the system -- you would essentially have to provide an unauthorized person access to your Mac while you were signed in before this would be an actual threat.

So, the most that can realistically happen is that if you leave your Mac unattended while logged in as Admin, a co-worker or friend might get in and install some app to play a prank on you.

I mean, unless somehow a malicious app has been approved on the Apple store and is available to download through the changed setting (and the "evil" co-worker/friend knows about it), but still the base security risk remains leaving the device unattended and making it phisically accessible by smeone else while still logged in as Admin.