Note that you can also run commands right in vi with the ! extended command, piping a range of lines through them. I use this with fmt all the time, and tend to prefer it over ctrl-z when I just want to check something.
True, but the ability to tab-complete commands/arguments is missing. But as you have said for something small it should just be fine.
Right, and you can search for (the start of) a command with up, when you've only got a few versions of something slightly longer that you use with moderate regularity. If you use them (or anything else) with high regularity, of course, bind them to a key sequence.