I am about to start cutting a very large project. Hours and hours of multi-clipped footage. We shoot with 2 EX1s. 1920x1080. We cut in 720p (extra room for cropping, etc) and then we master out to client requested 640x360 FLV files.
I will be cutting in either PP6 or FCP7. These projects get very large. My last FCP project file was....165mb itself. It crashed like crazy, even on a Macpro quad core xeon with 20 gigs of ram, and it even crashes in the version I created in PP6.0.
I have decided to look into perhaps doing an SD edit instead. I could render all of the footage out to SD ProRess LT. Cut in 720x480, and then render the FLVs from there.
SO the workflow would be to ingest everything at 1080. Render down to SD. Edit. Master. I would love in the end however to re-link everything to 1080 and master out from there....How would I do that?
Cutting SD or any timeline that doesn't match your footage will slow things down as lots of rendering and non RT performance will be the result. SD Prores is probably the same size or larger than HD XDCam, so no real saving in disk space.
One way that project files get huge is having lots of sequences. You can copy a sequence into a new project or periodically save as and delete older sequences which are still available if you need them in older saves.