I am a video professional, and use both AVCHD formats as well as HDV.
I have Sony HDV cameras, and a JVC AVCHD.
First the technical specs.
HDV is a 1080i format, that encodes at a resolution of 1440x1080.
The compression is MPG2 IPB frame with a color space 4:2:0
The data rate is fixed @ 25mbit.
AVCHD is encoded as H.264, which is MPG4
Most AVCHD cameras will claim full 1080, and some will claim 1080p output. They are all recording as a 1080i frame, and converting to 1080p when using the hdmi output. (My HDV equipment does the same, sends it to the tv as a 1080p signal over hdmi) The resolution is 1920x1080, so technically this would be a slightly sharper picture than the 1440x1080 that HDV records.
My JVC camera has 4 compression settings. 5meg, 12 meg, 15 meg and a whopping 24 meg.
The 3 lower bit rates are directly compatable with the AVCHD standard for optical disks, so disks made can directly be played on bluray players. The 24 meg format is over the spec for AVCHD, and can only be burned to real BDR disks, or transcoded to a lower bitrate for recording on conventional DVD-R media with compatability with blu ray players.
Most editing software these days will handle both HDV and AVCHD formats.
When I have done side by side tests comparing my AVCHD camera to my HDV cameras, I am hard pressed to see any real difference. They are very good. When it comes to editing, the AVC format is moch more finicky to work with. If is it a single camera personal video, then I may shoot it on my flash memory camera just because it is convient. If I am shooting anything 2 camera, or any commercial shoots that I know I am going to need to edit, then I shoot HDV, and leave the AVC camera at home. Why? The editing process for HDV is no different than for shooting DV. I plug the player into my old tired work station, and fire up Adobe Premiere pro, and capture my clips no differently than working with DV. In the background Cineform is making I frame versions of the IPB stream. Now I have frame accurate files that I can edit, in real time just like working with standard definition.
It is fast, accurate and has an unbeatable picture.
All of the consumer editing programs I have tried for AVCHD are so bloody limited that someone with my background has a real hard time figuring our how to so the simplest things. Once the project is edited I can output in whatever format I want. I can send it back to HDV which is whet I archive my material in, and I can also output an SD version for DVD distribution and AVCHD version for distribution on conventional DVDs that play i9n HD on bluray players.
@ 10 megs 60 minutes will go on a 4.7g disk. 2 hours will fit nicely on a dual layer disk.
Rendering takes about 3 hours for a 60 minute production shot and edited in HDV.
Now, if I had 60 minutes shot on AVCHD, take that time and multiply it by 3 and you get an idea how long it takes to render out from MPG4.
Basic cuts takes less time, but if there are transitions and effects, this really drags the system down to a crawl.
Another thing, I just happen to like tape. It is cheap, and you always have a reliable backup.
I keep all my master tapes just incase I ever need to go back and rework something, or need a shot that I know I have. Digital media is far too expensive to store (SD cards) and DVD's and hard drives are not reliable for long time storage. DVDs are easily damages by exposure to light, hard drives, lets not go there. Tape is reliable. I have tapes I recorded in the early 80's and they all play fine.
I also forgot to point out that due to the compression, h.264 video tends to degrade quickly with multi pass editing, or re-encoding
HDV since the compression is much lower stands up much better during the editing process.