frank,
there are some parameters missing in your question…
i’m assuming you captured your footage properly and used a timeline that matched its settings, OR that you don’t care for matching quality to the highest it could be but rather to the mentioned export.
in short, if you exported using your timeline settings, (say DV PAL, for example) you are not really exporting per say, but rather copying and rearranging files into a new container.
when you import in FCP, again, its not really an import, more like an alias, a place holder. which means that if you only do cuts on your re-imported export, (which you could actually do inside quicktime), on a timeline that matches its settings, and re-export using same settings. you should be fine.
unless you lost your footage, or FCP project, or never had it from the start… its a strange way to go.
peace.
Hector Berrebi
Schibber Group
prePost Consulting