Interesting - I use these so routinely it's unconscious, never had a problem. Though I suppose if I'm doing something remotely risky I'll not use them - though I'm not aware of doing that.

The class of shortcuts I love is:

[command] !:1-$

which copies the arguments to the previous command to this one. Or:

!:3

which copies the fourth argument.

Once those were under my fingers my fellow architects were astounded.