Why not use 120 FPS?

Considering that I DONT USE THE TIMELINE, and do all my Flash development purely in Actionscript, how important is my choice of frame rate?

It seems like a common choice is 24 FPS, so thats what Ive been using. But I got curious and cranked it up to 120 just for kicks. Now all my tweens and animations are beautifully smooth! I really don’t want to go back to 24 FPS, it seems so ugly by comparison. So the question is: Why would I??

Increasing the Frame Rate to 120 did not increase the SWF file size at all. Also, I opened up the task manager and watched the CPU usage while running both the 24 and the 120 FPS versions (and even a 2 FPS version). The CPU usage was the same (13%) in all cases. So thats not an issue.

I cant visually tell a difference between 120 FPS and 60 FPS, so I’ll be reasonable and set it down to 60. But lower than that you can start to notice a difference. So why would I ever want to lower the FPS below 60?

To me, 24 FPS means “play this movie as smooth as you can, but NOT smoother than 24FPS” Why would you want to artificially limit the movie like that? Maybe the computer is quite capabable of rendering 40 FPS. So what is the harm in asking it to try for 60?

Is there a down side to setting the FPS high? Or is that only if you are doing timeline based animation, in which case all your animations will occur faster than you intended.

Thanks!