Well I have been putting up with the terrible AVCHD editing experience with PE8 for long enough. I am going back to PE7.
The playback of AVCHD clips is like chalk and cheese between PE8 and PE7. In PE7 I can play back AVCHD clips without rendering and they play back "cleanly". With PE8 if you play back with out rendering the clips "break up"... is the best way I can put it. Also the playback is very jerky. Adobe have definately broken AVCHD playback in PE8. I have discussed this with other AVCHD users and they are seeing the same thing... and rolling back to PE7. Very dissapointing... especially as this issue was pointed out to them at an early stage.