Macs suck...
Nice to see another Mac user.
On the paysite that I manage we are now putting the movies small, med, large, giant, plus ipod and iphone.
As far as bandwidth it shouldn't make any difference if your member's download or stream. Some like to stream and some like to download so starting with a few updates ago
we started putting links for both as seen in this test template.
We use Episode Pro to encode our movies but it is an expensive program. I've never really used the H.264 export option in iMovie so I don't really know much about it but it should work although I hear it is painfully slow. The biggest issue for us with using the QuickTime export iMovie option is you really can't place a copyright image on the movie with it.
Episode Pro is a fantastic program but like I said very expensive. I saw
Stomp on MacInTouch.com this week. It looks like it might be useful but I know nothing about it.
Also
Elgato is making a hardware H.264 encoder that I see selling for around a hundred bucks. Haven't used it myself but it looks interesting.
Here is a screen shot of a directory showing file sizes of a 45 minute movie.