I agree. For JVC users, it's a boon to be able to add the clips directly to the timeline, but for Sony or Panasonic users, there is little benefit over the Vegas software. I'm thinking the ability to burn 3D Blu-ray will need more time to implement. It's there for the 2D software version of Edius. As for why they do things the way they do in the basic interface, it's probably programmers making the decisions, instead of users. Programmers don't think like normal human beings.
Playback for me is pretty smooth in Edius, even during 3D transitions (much smoother than Vegas), until I start adding zoom and convergence adjustments. That means that if I'm careful when I shoot and don't have to correct edge violations, editing in 3D is quite acceptable. That's a relief as well. I'm using the Edius preview on a Core i7 920 @ 2.66GHz, with SATAII SSDs, no HDDs. On 3D clips, I don't exceed about 65% CPU usage until I add adjustments. When I do, all 8 threads peg at 100%, and audio and video are choppy.
I've found that exporting to MPEG2 dual stream 3D files yields the best results in PowerDirector 10. AVCHD exports don't look as good, even at higher bitrates. I get excellent results with MPEG2 at 25mbps, compared to AVCHD 3D at 35mbps. Unless I'm configuring things wrong, the MVC encoder must not be nearly as good as the MPEG2 encoder. I get all sorts of undesirable artifacts with the MVC encoder. Again, it's possible I'm not configuring things correctly.