But it's only in 1 place that you have to look to change the code. What if you use the construct "arg$_" multiple times in the body of the loop? It will be slightly harder to change that, and make sure you have gotten them all.

Counting the keystrokes in my favorite editor to change arg to param in any of the above examples: ctrl-shift-5 a r g \n p a r a m \n !

12 keystrokes, easy enough. If you are worried about replacing other things, then it's +1 stroke per interactive search/replace....

Like FoxCub said, I think if you have both methods in your toolbox, and can use them when appropriate, then you are a better programmer for it.