I finally bothered to download the CS5.5 Master upgrade and it's installed now. My first run with Premiere Pro is good. The integration of the suite with interoperability is smooth and quick (PROVIDED you have a workstation computer). Took my old CS5 projects and converted with no problems. Everything runs native. I did a quick 4 track mix of R3D, H.264, Canon XF and AVCHD. All played at correct fps with ability to scrub etc and a few layers of EFX didn't slow it down. Watching CPU utilization, it used up all cores to do this on top of using the GPU. There's also background rendering and other neat features like the ability to switch between AEFX and PP, which automatically updates the other timeline with the modified clip. It even took my FCP project without a hitch.
This thing gobbles RAM if you have multiple programs running. I have 32GB and with AEFX and PP running @ 64bit on a smallish project, using RAM preview, I had 1GB left. Adobe recommends 2-3GB per processor, more in 64bit. I have 12 cores(24 with hyperthreading). Looks like I'll have to hope the 8GB sticks drop in price soon.
The integration is needed too as PP doesn't have many filters built into it. Image stabilization is pushed to AEFX, which is a bit silly but there are other 3rd party stabilization software like SmoothKit from RE:Vision.
Audition now replaces Soundbooth, a program I never liked. Have to play with it more to see if I can replace Pro Tools or Logic with it. Adobe Media Encoder is 64bit and multicore... will have to see how fast it renders.
New things to play with and not enough time!