We did 13 episodes of 3 camera multicam 24f that was onlined on a "unique" HD NLE called Mystika. Everything went by EDL. We started on FCP 5.1.1 and switched halfway to 5.1.2.
We had problems but not with the EDLs. Once the post facility had every Raw source in-house we could email them a zipped EDL and begin rendering out a reference QT while they pulled sources and conformed the EDL.
No Duck no XML, they weren't available options.
Can you verify your offline system's TC capture offsets, if there are any? Those migh get dumped after an upgrade or at least require recalibration.
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Sleeplings, AWAKE!