In a way it's easier to isolate the start and stop times in Audacity because you can listen to the song and pause it, readjust the cursor position if desired, etc. rather than having to enter numerical times into the iTunes fields.
Although you can't select different fade-in/out curves in Audacity like more ambitious studio editors, you can easily highlight the amount of seconds to apply the fade effects. And outside of studio editing, a linear fade-in/out is probably what you want anyway.
It's just a little more time consuming to use Audacity in conjunction with iTunes because of the extra file management steps required to open the file in Audacity and export back to the iTunes folder. But once you go through the procedure, it's not difficult.
BUT ..... now that I think about it, the iTunes start and stop times apply to playback from the iTunes database (in iTunes or an iPod), but I'm not sure if that will result in a shorter song when that file is burned to a CD. ? Haven't tried it.
Audacity is free, so you may want to download it and give it a try.
Steve