I just wanted to try it out ... and I had huge problems - the SUN tool does not work like it should according to the manual.
Here are my experiences/is my opinion:
Definitely: OmegaT is better than Xliff translation editor - the SUN tool is much too immature - I had to create a project us-EN to DE to be able to load the text-file (it was not possible to create a project with Italian as source language). Soft returns are not interpeted well (at least the title was mixed with the first sentence of the text). Generally speaking the segmentation does not really work well - there's no way to join segments to be able to work on a normal sentence. SUN should take OmegaT for their localisation work and hepl with internal segmentation + spellchecking + creating a glossary function - the SUN tool lacks even in this (glossary tool). So much money invested for that tool ... but how to tell this SUN? What I prefer is the way the translation units are shown in the SUN-Tool, but all the rest does not make me happy at all. A combination of both would be great.
Coding OpenOffice.org files with the XLIFF filter was not possible even if a "normal" OpenOffice.org file (I tried files of version 1.1 and 2.0beta). Something I can easily do with OmegaT - it opens OOo-files without an external conversion tool and therefore it is much easier to handle than the XLIFF Translation Editor.
Being presented as a "SUN inhouse tool that is used" I expected it to be much better and now I feel a bit disappointed ...
Definitely there is a lot to do - and combining forces would be the best thing to my opinion.
One thing has to be considered: the license the two tools use are different - but this should not be a hurdle I believe if people really want to co-operate.