I used 7toX to convert an XML for FCP7 to FCPX but a synced timeline is very unhandy to work with in FCPX. The editor could not do anything with it.
For syncing files in FCPX i really recommend Sync-N-Link-X. Not cheap, but it does do a lot of other things that we like; like setting rolls and channel names correctly.
If TC is recorded on an audio track use Tentacle Studio just to make new files for FCPX with the TC embedded in the metadata (file-tc)