The most recent version of ECS compatible with NCS 2.0-rc1 is ECS 2.0.3 (the latest in the 2.0 branch), which you can download from this web site). An yes, it includes a bug fix relative to UNV files, so it may work better for you.
In any case, I would recommend upgrading at least from 2.0-rc1 to 2.0.6 (3.0-rc1 is better, but will require more changes to your data setup). Version 2.0 will be maintained until version 4.0 is released (december 2014), while 2.0-beta and 2.0-rc versions are not maintained.
Thanks a lot for your answer ! My UNV mesh is well read with ECS 2.0.3.
Actually, I'm really interested in an upgrade from 2.0-rc1 to 2.0.6, but I can't find any release note concerning the differences "between those two versions". Are there only minor bug fixes ? I was not able to determine the SVN revisions corresponding so as to watch the logs...
For prerequisites, you would need to download them, to check their ChangeLogs.
For Code_Saturne 3.0, things are both simpler, as there is only one package, and more complex, as the current ChangeLog is autogenerated from subversion logs, and not versioned per se, though the NEWS file is versioned (the NEWS file is now "useful" in both version 2.0 and 3.0 branches, which was not the case even a few weeks ago).