Apple = Transcode = Mega huge extra files on top of the originals... lol
Native AVCHD is very easy to edit, but you have to get out of that restrictive Apple world.
Yes you can burn the 1920/1080 AVCHD files straight onto a DVD and play in a Blu_Ray player but AVCHD it a highly compressed codec to play so there could be some skipping if you go too high in the MBPS. (18 Mega Bytes Per Second Max) Also you are not going to get very much footage on a normal DVD disk.
AVCHD footage on a normal DVD may not play in all Blu_Ray players.
You can however just make normal 720/576 DVD's but it will not be 1920/1080.
Its best to edit the AVCHD, then render out a 1920/1080 H.264 or the easier but takes up more room 25 MBPS MPEG2, author the Blu_Ray, compile it, check it.... then burn away.
You can get 90 minutes of 1920/1080 @ 25MBPS MPEG2 on a 25 GIG Blu_Ray disk easy.