At 28 mbps, multiplexed AVCHD 2.0 L/R streams are 14 mbps each. At 24/25 mbps, MVC video is roughly 16 mbps for the primary stream and 8 mbps for the dependent right eye stream. So, it's really 14 vs 16 mbps, and AVCHD video at that data rate can look very good. Add in the fact that you don't compromise the frame rate (no 60i to 24p conversion to muck up the motion), and I wager the AVCHD 2.0 streams will still look significantly better if the encoding is good.
My problem in the past was that I had problems with 3D displays and players not being able to handle the AVCHD 2.0 "standard." I ran into compatibility issues, where the video on the disc wasn't read by the player or the resolution took a hit on the display. I gave up. I went back to my current workflow - edit in Edius, export L/R AVCHD 1080/60i files for Vegas, then let Vegas do the de-interlacing from 60i to 24p and create the Blu-ray 3D. The biggest benefit is that I don't have to worry about compatibility, because Vegas creates Blu-ray 3D discs that will play on virtually any Blu-ray 3D player.
These reports from shearer69 give me hope that I might have more success now. It's worth a try. If I run into the same old issues, I'm no worse off than before.
PS - it's generally assumed that AVCHD is roughly equivalent to MPEG2 encoding, but uses only half the data rate. So, a 14 mbps AVCHD stream should be about the same quality as a 28 mbps MPEG2 stream. Current broadcasts in the US use the ATSC standard, which is MPEG2 at about 20 mbps. If the full bandwidth is used (almost never anymore
), the quality is quite good. The point is that video can be encoded with lower bitrate AVCHD with excellent results, especially considering that encoding techniques have improved since the standard was released. Not having to worry about motion issues created by the 60i to 24p conversion step is a huge plus.