RichFaces not only works with SEAM, it's nicely integrated with SEAM. The chosen view technology for SEAM is... facelets.
I know that RichFaces is fully integrated with SEAM, of course it's from the same comunity. But ICEFaces is also integrated with SEAM, and of course with other frameworks. So, if you are using SEAM the comunity encourage the use of RF, or IF as you want.
Also, newer versions of the RichFaces framework DO provide an AJAX Push mechanism.
Never have tested RF Ajax Push but ICEFaces Ajax Push, and it works almost excelent.
Of course, it's a matter of several variables decision. What you have knowledge, what is using in your company, what is more standard (relative), what you like more :-), etc.
I still using IF (and have worked with both) when I have the opportunity to choose.
If you like to have a bit more control in your hands you may prefer RF. If you trust your framework you will like IF
Will be pretty interesting how this will look like with the implementations for the new JSF 2.0. The new standard itself is more like RF today ;-)
Well, IF already did it the first time when JSF 1 didn't come with an easy AJAX extension capability, so you can bet that they do it again ... and they will use the new JSF 2 features and will bring us the new IF framework ... it's why JSF was conceived, to allow this kind of frameworks development above it.
I was really attracted to that with IF, but in the end I had to go with RF (not my decision)
When you can decide then give a try to IF more deep, then (as you know more RF) you will take a better final decision.