For the AVCHD video the audio appears to be fine, though that was shot on native, 24p, so all I was doing was changing the video to easier to edit AVI footage.
I shot on another camera, a Canon Vixia HV30, on tape to 24fps, which is in a 60i wrapper. I used Cineform Neoscene to do the pulldown so I could cut the footage with the AVCHD footage I shot.
The audio is a few frames out of synch. I tried ungrouping the audio and video on the timeline in Vegas to synch them, but it gets out of synch more than once in the video, and I'm having a hard time figuring out where, other than the very beginning, in the video that the audio goes out of synch. It's only by a few frames.
Some other people have had the same problem but I haven't seen any solutions posted online. I guess I could change my AC3 Filter settings since you can adjust something about the audio's speed with the video, but I'm not sure how I should do that.
I also ran into the sync problem using NeoScene converting HDV footage. The audio of the cineform converted footage is ahead of the video by 2-3 frames. In contrast, the captured m2t file has its audio and video in sync.
I've tested this out using some HDV footage (captured shot of a standard film clapboard using a Z1U) and have put the m2t files and the converted files on the Vegas timeline. There is definitely an offset.
I didn't change frame rates either. The m2t file was at 29.97fps and the conversion was left at the same rate.