I use both SWiSH and Flash, and for me SWiSH is a godsend. I really only use flash for sounds, preloaders, and colour images that work work as image fonts.

I have seen articles in different threads that the file size in SWiSH is the same as it would be in Flash - if someone had taken the time to recreate the same text effects.

The main reason that swish files become big is that everyone is tempted to throw everything in, just because you can - and you know that only experienced Flash people could do the same. As a result the files can become bloated.